rslib: Cleanup and VLA removal

From: Thomas Gleixner <[email protected]>

The Reed-Solomon library is based on code from Phil Karn who granted permission to import it into the kernel under the GPL V2.

See commit 15b5423757a7 ("Shared Reed-Solomon ECC library") in the history git tree at: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git

...
The encoder/decoder code is lifted from the GPL'd userspace RS-library written by Phil Karn. I modified/wrapped it to provide the different functions which we need in the MTD/NAND code.
...

Signed-off-by Thomas Gleixner <[email protected]>

Signed-off-by David Woodhouse <[email protected]>

"No objections at all. Just keep the authorship notices." -- Phil Karn

Add the proper SPDX identifiers according to
Documentation/process/license-rules.rst.

Signed-off-by Thomas Gleixner <[email protected]>

Cc Kate Stewart <[email protected]>

Cc Boris Brezillon <[email protected]>

Cc Tony Luck <[email protected]>

Cc Kees Cook <[email protected]>

Cc Segher Boessenkool <[email protected]>

Cc Kernel Hardening <[email protected]>

Cc Richard Weinberger <[email protected]>

Cc Mike Snitzer <[email protected]>

Cc Anton Vorontsov <[email protected]>

Cc Greg Kroah-Hartman <[email protected]>

Cc Colin Cross <[email protected]>

Cc Andrew Morton <[email protected]>

Cc David Woodhouse <[email protected]>

Cc Alasdair Kergon <[email protected]>

From: Thomas Gleixner <[email protected]>

The Reed-Solomon library is based on code from Phil Karn who granted permission to import it into the kernel under the GPL V2.

See commit 15b5423757a7 ("Shared Reed-Solomon ECC library") in the history git tree at: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.
git

...
The encoder/decoder code is lifted from the GPL'd userspace RS-library written by Phil Karn. I modified/wrapped it to provide the different functions which we need in the MTD/NAND code.
...

Signed-off-by Thomas Gleixner <[email protected]>

Signed-off-by David Woodhouse <[email protected]>

"No objections at all. Just keep the authorship notices." -- Phil Karn

Add the proper SPDX identifiers according to
Documentation/process/license-rules.rst.

Signed-off-by Thomas Gleixner <[email protected]>

Cc Boris Brezillon <[email protected]>

Cc Tony Luck <[email protected]>

Cc Kees Cook <[email protected]>

Cc Segher Boessenkool <[email protected]>

Cc Kernel Hardening <[email protected]>

Cc Richard Weinberger <[email protected]>

Cc Mike Snitzer <[email protected]>

Cc Anton Vorontsov <[email protected]>

Cc Greg Kroah-Hartman <[email protected]>

Cc Colin Cross <[email protected]>

Cc Andrew Morton <[email protected]>

Cc David Woodhouse <[email protected]>

Cc Alasdair Kergon <[email protected]>

Reviewed-by Kate Stewart <[email protected]>

From: Thomas Gleixner <[email protected]>

Now that SPDX identifiers are in place, remove the GPL boiler plate text. Leave the notices which document that Phil Karn granted permission in place (encode/decode source code). The modified files are code written for the kernel by me.

Signed-off-by Thomas Gleixner <[email protected]>

Cc Kate Stewart <[email protected]>

Cc Boris Brezillon <[email protected]>

Cc Tony Luck <[email protected]>

Cc Kees Cook <[email protected]>

Cc Segher Boessenkool <[email protected]>

Cc Kernel Hardening <[email protected]>

Cc Richard Weinberger <[email protected]>

Cc Mike Snitzer <[email protected]>

Cc Anton Vorontsov <[email protected]>

Cc Greg Kroah-Hartman <[email protected]>

Cc Colin Cross <[email protected]>

Cc Andrew Morton <[email protected]>

Cc David Woodhouse <[email protected]>

Cc Alasdair Kergon <[email protected]>

From: Thomas Gleixner <[email protected]>

Now that SPDX identifiers are in place, remove the GPL boiler plate text. Leave the notices which document that Phil Karn granted permission in place (encode/decode source code). The modified files are code written for the kernel by me.

Signed-off-by Thomas Gleixner <[email protected]>

Cc Boris Brezillon <[email protected]>

Cc Tony Luck <[email protected]>

Cc Kees Cook <[email protected]>

Cc Segher Boessenkool <[email protected]>

Cc Kernel Hardening <[email protected]>

Cc Richard Weinberger <[email protected]>

Cc Mike Snitzer <[email protected]>

Cc Anton Vorontsov <[email protected]>

Cc Greg Kroah-Hartman <[email protected]>

Cc Colin Cross <[email protected]>

Cc Andrew Morton <[email protected]>

Cc David Woodhouse <[email protected]>

Cc Alasdair Kergon <[email protected]>

From: Thomas Gleixner <[email protected]>

The decoder library uses variable length arrays on stack. To get rid of them it would be simple to allocate fixed length arrays on stack, but those might become rather large. The other solution is to allocate the buffers in the rs control structure, but this cannot be done as long as the structure can be shared by several users. Sharing is desired because the RS polynom tables are large and initialization is time consuming.

To solve this split the codec information out of the control structure and have a pointer to a shared codec in it. Instantiate the control structure for each user, create a new codec if no shareable is avaiable yet. Adjust all affected usage sites to the new scheme.

This allows to add per instance decoder buffers to the control structure later on.

Signed-off-by Thomas Gleixner <[email protected]>

Cc Boris Brezillon <[email protected]>

Cc Tony Luck <[email protected]>

Cc Kees Cook <[email protected]>

Cc Segher Boessenkool <[email protected]>

Cc Kernel Hardening <[email protected]>

Cc Richard Weinberger <[email protected]>

Cc Mike Snitzer <[email protected]>

Cc Anton Vorontsov <[email protected]>

Cc Colin Cross <[email protected]>

Cc Andrew Morton <[email protected]>

Cc David Woodhouse <[email protected]>

Cc Alasdair Kergon <[email protected]>

---
 drivers/mtd/nand/raw/cafe_nand.c    |    7 +
 drivers/mtd/nand/raw/diskonchip.c   |    7 +

 include/linux/rslib.h           |   18 +++--
 lib/reed_solomon/decode_rs.c    |    1 
 lib/reed_solomon/encode_rs.c    |    1 
 lib/reed_solomon/reed_solomon.c |  144 ++++++++++++++++++++++------------------
 6 files changed, 104 insertions(+), 74 deletions(-)

drivers/mtd/nand/raw/cafe_nand.c +4 -3

@@ -394,12 +394,13 @@ static int cafe_nand_read_page(struct mt
 
 		for (i=0; i<8; i+=2) {
 			uint32_t tmp = cafe_readl(cafe, NAND_ECC_SYN01 + (i*2));
-			syn[i] = cafe->rs->index_of[tmp & 0xfff];
-			syn[i+1] = cafe->rs->index_of[(tmp >> 16) & 0xfff];
+
+			syn[i] = cafe->rs->codec->index_of[tmp & 0xfff];
+			syn[i+1] = cafe->rs->codec->index_of[(tmp >> 16) & 0xfff];
 		}
 
 		n = decode_rs16(cafe->rs, NULL, NULL, 1367, syn, 0, pos, 0,
-		                pat);
+				pat);
 
 		for (i = 0; i < n; i++) {
 			int p = pos[i];

drivers/mtd/nand/raw/diskonchip.c +4 -3

@@ -142,6 +142,7 @@ static int doc_ecc_decode(struct rs_cont
 	int i, j, nerr, errpos[8];
 	uint8_t parity;
 	uint16_t ds[4], s[5], tmp, errval[8], syn[4];
+	struct rs_codec *cd = rs->codec;
 
 	memset(syn, 0, sizeof(syn));
 	/* Convert the ecc bytes into words */

@@ -162,15 +163,15 @@ static int doc_ecc_decode(struct rs_cont
 	for (j = 1; j < NROOTS; j++) {
 		if (ds[j] == 0)
 			continue;
-		tmp = rs->index_of[ds[j]];
+		tmp = cd->index_of[ds[j]];
 		for (i = 0; i < NROOTS; i++)
-			s[i] ^= rs->alpha_to[rs_modnn(rs, tmp + (FCR + i) * j)];
+			s[i] ^= cd->alpha_to[rs_modnn(cd, tmp + (FCR + i) * j)];
 	}
 
 	/* Calc syn[i] = s[i] / alpha^(v + i) */
 	for (i = 0; i < NROOTS; i++) {
 		if (s[i])
-			syn[i] = rs_modnn(rs, rs->index_of[s[i]] + (NN - FCR - i));
+			syn[i] = rs_modnn(cd, cd->index_of[s[i]] + (NN - FCR - i));
 	}
 	/* Call the decoder library */
 	nerr = decode_rs16(rs, NULL, NULL, 1019, syn, 0, errpos, 0, errval);

include/linux/rslib.h +13 -5

@@ -13,7 +13,7 @@
 #include <linux/list.h>
 
 /**
- * struct rs_control - rs control structure
+ * struct rs_codec - rs codec data
  *
  * @mm:		Bits per symbol
  * @nn:		Symbols per block (= (1<<mm)-1)

@@ -27,9 +27,9 @@
  * @gfpoly:	The primitive generator polynominal
  * @gffunc:	Function to generate the field, if non-canonical representation
  * @users:	Users of this structure
- * @list:	List entry for the rs control list
+ * @list:	List entry for the rs codec list
 */
-struct rs_control {
+struct rs_codec {
 	int		mm;
 	int		nn;
 	uint16_t	*alpha_to;

@@ -45,6 +45,14 @@ struct rs_control {
 	struct list_head list;
 };
 
+/**
+ * struct rs_control - rs control structure per instance
+ * @codec:	The codec used for this instance
+ */
+struct rs_control {
+	struct rs_codec	*codec;
+};
+
 /* General purpose RS codec, 8-bit data width, symbol width 1-15 bit  */
 #ifdef CONFIG_REED_SOLOMON_ENC8
 int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,

@@ -78,7 +86,7 @@ void free_rs(struct rs_control *rs);
 
 /** modulo replacement for galois field arithmetics
  *
- *  @rs:	the rs control structure
+ *  @rs:	Pointer to the RS codec
  *  @x:		the value to reduce
  *
  *  where

@@ -88,7 +96,7 @@ void free_rs(struct rs_control *rs);
  *  Simple arithmetic modulo would return a wrong result for values
  *  >= 3 * rs->nn
 */
-static inline int rs_modnn(struct rs_control *rs, int x)
+static inline int rs_modnn(struct rs_codec *rs, int x)
 {
 	while (x >= rs->nn) {
 		x -= rs->nn;

lib/reed_solomon/decode_rs.c +1 -0

@@ -10,6 +10,7 @@
  * Generic data width independent code which is included by the wrappers.
  */
 {
+	struct rs_codec *rs = rsc->codec;
 	int deg_lambda, el, deg_omega;
 	int i, j, r, k, pad;
 	int nn = rs->nn;

lib/reed_solomon/encode_rs.c +1 -0

@@ -10,6 +10,7 @@
  * Generic data width independent code which is included by the wrappers.
  */
 {
+	struct rs_codec *rs = rsc->codec;
 	int i, j, pad;
 	int nn = rs->nn;
 	int nroots = rs->nroots;

lib/reed_solomon/reed_solomon.c +81 -63

@@ -11,22 +11,23 @@
  *
  * The generic Reed Solomon library provides runtime configurable
  * encoding / decoding of RS codes.
- * Each user must call init_rs to get a pointer to a rs_control
- * structure for the given rs parameters. This structure is either
- * generated or a already available matching control structure is used.
- * If a structure is generated then the polynomial arrays for
- * fast encoding / decoding are built. This can take some time so
- * make sure not to call this function from a time critical path.
- * Usually a module / driver should initialize the necessary
- * rs_control structure on module / driver init and release it
- * on exit.
- * The encoding puts the calculated syndrome into a given syndrome
- * buffer.
- * The decoding is a two step process. The first step calculates
- * the syndrome over the received (data + syndrome) and calls the
- * second stage, which does the decoding / error correction itself.
- * Many hw encoders provide a syndrome calculation over the received
- * data + syndrome and can call the second stage directly.
+ *
+ * Each user must call init_rs to get a pointer to a rs_control structure
+ * for the given rs parameters. The control struct is unique per instance.
+ * It points to a codec which can be shared by multiple control structures.
+ * If a codec is newly allocated then the polynomial arrays for fast
+ * encoding / decoding are built. This can take some time so make sure not
+ * to call this function from a time critical path.  Usually a module /
+ * driver should initialize the necessary rs_control structure on module /
+ * driver init and release it on exit.
+ *
+ * The encoding puts the calculated syndrome into a given syndrome buffer.
+ *
+ * The decoding is a two step process. The first step calculates the
+ * syndrome over the received (data + syndrome) and calls the second stage,
+ * which does the decoding / error correction itself.  Many hw encoders
+ * provide a syndrome calculation over the received data + syndrome and can
+ * call the second stage directly.
  */
 #include <linux/errno.h>
 #include <linux/kernel.h>

@@ -36,13 +37,13 @@
 #include <linux/slab.h>
 #include <linux/mutex.h>
 
-/* This list holds all currently allocated rs control structures */
-static LIST_HEAD (rslist);
+/* This list holds all currently allocated rs codec structures */
+static LIST_HEAD(codec_list);
 /* Protection for the list */
 static DEFINE_MUTEX(rslistlock);
 
 /**
- * rs_init - Initialize a Reed-Solomon codec
+ * codec_init - Initialize a Reed-Solomon codec
  * @symsize:	symbol size, bits (1-8)
  * @gfpoly:	Field generator polynomial coefficients
  * @gffunc:	Field generator function

@@ -50,18 +51,17 @@ static DEFINE_MUTEX(rslistlock);
  * @prim:	primitive element to generate polynomial roots
  * @nroots:	RS code generator polynomial degree (number of roots)
  *
- * Allocate a control structure and the polynom arrays for faster
+ * Allocate a codec structure and the polynom arrays for faster
  * en/decoding. Fill the arrays according to the given parameters.
  */
-static struct rs_control *rs_init(int symsize, int gfpoly, int (*gffunc)(int),
-				  int fcr, int prim, int nroots)
+static struct rs_codec *codec_init(int symsize, int gfpoly, int (*gffunc)(int),
+				   int fcr, int prim, int nroots)
 {
-	struct rs_control *rs;
 	int i, j, sr, root, iprim;
+	struct rs_codec *rs;
 
-	/* Allocate the control structure */
-	rs = kmalloc(sizeof (struct rs_control), GFP_KERNEL);
-	if (rs == NULL)
+	rs = kmalloc(sizeof(*rs), GFP_KERNEL);
+	if (!rs)
 		return NULL;
 
 	INIT_LIST_HEAD(&rs->list);

@@ -138,6 +138,9 @@ static struct rs_control *rs_init(int sy
 	/* convert rs->genpoly[] to index form for quicker encoding */
 	for (i = 0; i <= nroots; i++)
 		rs->genpoly[i] = rs->index_of[rs->genpoly[i]];
+
+	rs->users = 1;
+	list_add(&rs->list, &codec_list);
 	return rs;
 
 	/* Error exit */

@@ -154,26 +157,36 @@ static struct rs_control *rs_init(int sy
 
 
 /**
- *  free_rs - Free the rs control structure, if it is no longer used
- *  @rs:	the control structure which is not longer used by the
+ *  free_rs - Free the rs control structure
+ *  @rs:	The control structure which is not longer used by the
  *		caller
+ *
+ * Free the control structure. If @rs is the last user of the associated
+ * codec, free the codec as well.
  */
 void free_rs(struct rs_control *rs)
 {
+	struct rs_codec *cd;
+
+	if (!rs)
+		return;
+
+	cd = rs->codec;
 	mutex_lock(&rslistlock);
-	rs->users--;
-	if(!rs->users) {
-		list_del(&rs->list);
-		kfree(rs->alpha_to);
-		kfree(rs->index_of);
-		kfree(rs->genpoly);
-		kfree(rs);
+	cd->users--;
+	if(!cd->users) {
+		list_del(&cd->list);
+		kfree(cd->alpha_to);
+		kfree(cd->index_of);
+		kfree(cd->genpoly);
+		kfree(cd);
 	}
 	mutex_unlock(&rslistlock);
+	kfree(rs);
 }
 
 /**
- * init_rs_internal - Find a matching or allocate a new rs control structure
+ * init_rs_internal - Allocate rs control, find a matching codec or allocate a new one
  *  @symsize:	the symbol size (number of bits)
  *  @gfpoly:	the extended Galois field generator polynomial coefficients,
  *		with the 0th coefficient in the low order bit. The polynomial

@@ -190,8 +203,8 @@ static struct rs_control *init_rs_intern
 					   int (*gffunc)(int), int fcr,
 					   int prim, int nroots)
 {
-	struct list_head	*tmp;
-	struct rs_control	*rs;
+	struct list_head *tmp;
+	struct rs_control *rs;
 
 	/* Sanity checks */
 	if (symsize < 1)

@@ -203,33 +216,39 @@ static struct rs_control *init_rs_intern
 	if (nroots < 0 || nroots >= (1<<symsize))
 		return NULL;
 
+	rs = kzalloc(sizeof(*rs), GFP_KERNEL);
+	if (!rs)
+		return NULL;
+
 	mutex_lock(&rslistlock);
 
 	/* Walk through the list and look for a matching entry */
-	list_for_each(tmp, &rslist) {
-		rs = list_entry(tmp, struct rs_control, list);
-		if (symsize != rs->mm)
+	list_for_each(tmp, &codec_list) {
+		struct rs_codec *cd = list_entry(tmp, struct rs_codec, list);
+
+		if (symsize != cd->mm)
 			continue;
-		if (gfpoly != rs->gfpoly)
+		if (gfpoly != cd->gfpoly)
 			continue;
-		if (gffunc != rs->gffunc)
+		if (gffunc != cd->gffunc)
 			continue;
-		if (fcr != rs->fcr)
+		if (fcr != cd->fcr)
 			continue;
-		if (prim != rs->prim)
+		if (prim != cd->prim)
 			continue;
-		if (nroots != rs->nroots)
+		if (nroots != cd->nroots)
 			continue;
 		/* We have a matching one already */
-		rs->users++;
+		cd->users++;
+		rs->codec = cd;
 		goto out;
 	}
 
 	/* Create a new one */
-	rs = rs_init(symsize, gfpoly, gffunc, fcr, prim, nroots);
-	if (rs) {
-		rs->users = 1;
-		list_add(&rs->list, &rslist);
+	rs->codec = codec_init(symsize, gfpoly, gffunc, fcr, prim, nroots);
+	if (!rs->codec) {
+		kfree(rs);
+		rs = NULL;
 	}
 out:
 	mutex_unlock(&rslistlock);

@@ -237,7 +256,7 @@ static struct rs_control *init_rs_intern
 }
 
 /**
- * init_rs - Find a matching or allocate a new rs control structure
+ * init_rs - Create a RS control struct and initialize it
  *  @symsize:	the symbol size (number of bits)
  *  @gfpoly:	the extended Galois field generator polynomial coefficients,
  *		with the 0th coefficient in the low order bit. The polynomial

@@ -254,9 +273,8 @@ struct rs_control *init_rs(int symsize,
 }
 
 /**
- * init_rs_non_canonical - Find a matching or allocate a new rs control
- *                         structure, for fields with non-canonical
- *                         representation
+ * init_rs_non_canonical - Allocate rs control struct for fields with
+ *                         non-canonical representation
  *  @symsize:	the symbol size (number of bits)
  *  @gffunc:	pointer to function to generate the next field element,
  *		or the multiplicative identity element if given 0.  Used

@@ -275,7 +293,7 @@ struct rs_control *init_rs_non_canonical
 #ifdef CONFIG_REED_SOLOMON_ENC8
 /**
  *  encode_rs8 - Calculate the parity for data values (8bit data width)
- *  @rs:	the rs control structure
+ *  @rsc:	the rs control structure
  *  @data:	data field of a given type
  *  @len:	data length
  *  @par:	parity data, must be initialized by caller (usually all 0)

@@ -285,7 +303,7 @@ struct rs_control *init_rs_non_canonical
  *  symbol size > 8. The calling code must take care of encoding of the
  *  syndrome result for storage itself.
  */
-int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,
+int encode_rs8(struct rs_control *rsc, uint8_t *data, int len, uint16_t *par,
 	       uint16_t invmsk)
 {
 #include "encode_rs.c"

@@ -296,7 +314,7 @@ EXPORT_SYMBOL_GPL(encode_rs8);
 #ifdef CONFIG_REED_SOLOMON_DEC8
 /**
  *  decode_rs8 - Decode codeword (8bit data width)
- *  @rs:	the rs control structure
+ *  @rsc:	the rs control structure
  *  @data:	data field of a given type
  *  @par:	received parity data field
  *  @len:	data length

@@ -311,7 +329,7 @@ EXPORT_SYMBOL_GPL(encode_rs8);
  *  syndrome result and the received parity before calling this code.
  *  Returns the number of corrected bits or -EBADMSG for uncorrectable errors.
  */
-int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len,
+int decode_rs8(struct rs_control *rsc, uint8_t *data, uint16_t *par, int len,
 	       uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
 	       uint16_t *corr)
 {

@@ -323,7 +341,7 @@ EXPORT_SYMBOL_GPL(decode_rs8);
 #ifdef CONFIG_REED_SOLOMON_ENC16
 /**
  *  encode_rs16 - Calculate the parity for data values (16bit data width)
- *  @rs:	the rs control structure
+ *  @rsc:	the rs control structure
  *  @data:	data field of a given type
  *  @len:	data length
  *  @par:	parity data, must be initialized by caller (usually all 0)

@@ -331,7 +349,7 @@ EXPORT_SYMBOL_GPL(decode_rs8);
  *
  *  Each field in the data array contains up to symbol size bits of valid data.
  */
-int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par,
+int encode_rs16(struct rs_control *rsc, uint16_t *data, int len, uint16_t *par,
 	uint16_t invmsk)
 {
 #include "encode_rs.c"

@@ -342,7 +360,7 @@ EXPORT_SYMBOL_GPL(encode_rs16);
 #ifdef CONFIG_REED_SOLOMON_DEC16
 /**
  *  decode_rs16 - Decode codeword (16bit data width)
- *  @rs:	the rs control structure
+ *  @rsc:	the rs control structure
  *  @data:	data field of a given type
  *  @par:	received parity data field
  *  @len:	data length

@@ -355,7 +373,7 @@ EXPORT_SYMBOL_GPL(encode_rs16);
  *  Each field in the data array contains up to symbol size bits of valid data.
  *  Returns the number of corrected bits or -EBADMSG for uncorrectable errors.
  */
-int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len,
+int decode_rs16(struct rs_control *rsc, uint16_t *data, uint16_t *par, int len,
 		uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
 		uint16_t *corr)
 {

From: Thomas Gleixner <[email protected]>

The reed solomon library is moving the on stack decoder buffers into the rs control structure. That would break the DoC driver because multiple instances share the same control structure and can operate in parallel. At least in theory....

Instantiate a rs control instance per DoC device to avoid that. The per instance buffer is fine as the operation on a single DoC instance is serialized by the MTD/NAND core.

Signed-off-by Thomas Gleixner <[email protected]>

Cc Boris Brezillon <[email protected]>

Cc Tony Luck <[email protected]>

Cc Kees Cook <[email protected]>

Cc Segher Boessenkool <[email protected]>

Cc Kernel Hardening <[email protected]>

Cc Richard Weinberger <[email protected]>

Cc Mike Snitzer <[email protected]>

Cc Anton Vorontsov <[email protected]>

Cc Colin Cross <[email protected]>

Cc Andrew Morton <[email protected]>

Cc David Woodhouse <[email protected]>

Cc Alasdair Kergon <[email protected]>

---
 drivers/mtd/nand/raw/diskonchip.c |   60 +++++++++++++++++---------------------
 1 file changed, 27 insertions(+), 33 deletions(-)

drivers/mtd/nand/raw/diskonchip.c +27 -33

@@ -66,6 +66,7 @@ struct doc_priv {
 	int curchip;
 	int mh0_page;
 	int mh1_page;
+	struct rs_control *rs_decoder;
 	struct mtd_info *nextdoc;
 
 	/* Handle the last stage of initialization (BBT scan, partitioning) */

@@ -123,9 +124,6 @@ MODULE_PARM_DESC(doc_config_location, "P
 /* Number of symbols */
 #define NN 1023
 
-/* the Reed Solomon control structure */
-static struct rs_control *rs_decoder;
-
 /*
  * The HW decoder in the DoC ASIC's provides us a error syndrome,
  * which we must convert to a standard syndrome usable by the generic

@@ -931,7 +929,7 @@ static int doc200x_correct_data(struct m
 				calc_ecc[i] = ReadDOC_(docptr, DoC_ECCSyndrome0 + i);
 		}
 
-		ret = doc_ecc_decode(rs_decoder, dat, calc_ecc);
+		ret = doc_ecc_decode(doc->rs_decoder, dat, calc_ecc);
 		if (ret > 0)
 			pr_err("doc200x_correct_data corrected %d errors\n",
 			       ret);

@@ -1422,10 +1420,10 @@ static inline int __init doc2001plus_ini
 
 static int __init doc_probe(unsigned long physadr)
 {
+	struct nand_chip *nand = NULL;
+	struct doc_priv *doc = NULL;
 	unsigned char ChipID;
 	struct mtd_info *mtd;
-	struct nand_chip *nand;
-	struct doc_priv *doc;
 	void __iomem *virtadr;
 	unsigned char save_control;
 	unsigned char tmp, tmpb, tmpc;

@@ -1562,8 +1560,25 @@ static int __init doc_probe(unsigned lon
 		goto fail;
 	}
 
+
+	/*
+	 * Allocate a RS codec instance
+	 *
+	 * Symbolsize is 10 (bits)
+	 * Primitve polynomial is x^10+x^3+1
+	 * First consecutive root is 510
+	 * Primitve element to generate roots = 1
+	 * Generator polinomial degree = 4
+	 */
+	doc = (struct doc_priv *) (nand + 1);
+	doc->rs_decoder = init_rs(10, 0x409, FCR, 1, NROOTS);
+	if (!doc->rs_decoder) {
+		pr_err("DiskOnChip: Could not create a RS codec\n");
+		ret = -ENOMEM;
+		goto fail;
+	}
+
 	mtd			= nand_to_mtd(nand);
-	doc			= (struct doc_priv *) (nand + 1);
 	nand->bbt_td		= (struct nand_bbt_descr *) (doc + 1);
 	nand->bbt_md		= nand->bbt_td + 1;
 

@@ -1613,7 +1628,6 @@ static int __init doc_probe(unsigned lon
 		   haven't yet added it.  This is handled without incident by
 		   mtd_device_unregister, as far as I can tell. */
 		nand_release(mtd);
-		kfree(nand);
 		goto fail;
 	}
 

@@ -1626,6 +1640,9 @@ static int __init doc_probe(unsigned lon
 	   actually a DiskOnChip.  */
 	WriteDOC(save_control, virtadr, DOCControl);
  fail:
+	if (doc)
+		free_rs(doc->rs_decoder);
+	kfree(nand);
 	iounmap(virtadr);
 
 error_ioremap:

@@ -1648,6 +1665,7 @@ static void release_nanddoc(void)
 		nand_release(mtd);
 		iounmap(doc->virtadr);
 		release_mem_region(doc->physadr, DOC_IOREMAP_LEN);
+		free_rs(doc->rs_decoder);
 		kfree(nand);
 	}
 }

@@ -1656,27 +1674,12 @@ static int __init init_nanddoc(void)
 {
 	int i, ret = 0;
 
-	/* We could create the decoder on demand, if memory is a concern.
-	 * This way we have it handy, if an error happens
-	 *
-	 * Symbolsize is 10 (bits)
-	 * Primitve polynomial is x^10+x^3+1
-	 * first consecutive root is 510
-	 * primitve element to generate roots = 1
-	 * generator polinomial degree = 4
-	 */
-	rs_decoder = init_rs(10, 0x409, FCR, 1, NROOTS);
-	if (!rs_decoder) {
-		pr_err("DiskOnChip: Could not create a RS decoder\n");
-		return -ENOMEM;
-	}
-
 	if (doc_config_location) {
 		pr_info("Using configured DiskOnChip probe address 0x%lx\n",
 			doc_config_location);
 		ret = doc_probe(doc_config_location);
 		if (ret < 0)
-			goto outerr;
+			return ret;
 	} else {
 		for (i = 0; (doc_locations[i] != 0xffffffff); i++) {
 			doc_probe(doc_locations[i]);

@@ -1687,11 +1690,7 @@ static int __init init_nanddoc(void)
 	if (!doclist) {
 		pr_info("No valid DiskOnChip devices found\n");
 		ret = -ENODEV;
-		goto outerr;
 	}
-	return 0;
- outerr:
-	free_rs(rs_decoder);
 	return ret;
 }
 

@@ -1699,11 +1698,6 @@ static void __exit cleanup_nanddoc(void)
 {
 	/* Cleanup the nand/DoC resources */
 	release_nanddoc();
-
-	/* Free the reed solomon resources */
-	if (rs_decoder) {
-		free_rs(rs_decoder);
-	}
 }
 
 module_init(init_nanddoc);

From: Thomas Gleixner <[email protected]>

The allocation of the reed solomon control structure can fail, but fec_alloc_bufs() ignores that and subsequent operations in dm verity use the potential NULL pointer unconditionally.

Add a proper check and abort if init_rs() fails.

Signed-off-by Thomas Gleixner <[email protected]>

Cc Boris Brezillon <[email protected]>

Cc Tony Luck <[email protected]>

Cc Kees Cook <[email protected]>

Cc Segher Boessenkool <[email protected]>

Cc Kernel Hardening <[email protected]>

Cc Richard Weinberger <[email protected]>

Cc Mike Snitzer <[email protected]>

Cc Anton Vorontsov <[email protected]>

Cc Colin Cross <[email protected]>

Cc Andrew Morton <[email protected]>

Cc David Woodhouse <[email protected]>

Cc Alasdair Kergon <[email protected]>

---
 drivers/md/dm-verity-fec.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

drivers/md/dm-verity-fec.c +6 -1

@@ -308,8 +308,13 @@ static int fec_alloc_bufs(struct dm_veri
 {
 	unsigned n;
 
-	if (!fio->rs)
+	if (!fio->rs) {
 		fio->rs = mempool_alloc(v->fec->rs_pool, GFP_NOIO);
+		if (!fio->rs) {
+			DMERR("failed to allocate RS control structure");
+			return -ENOMEM;
+		}
+	}
 
 	fec_for_each_prealloc_buffer(n) {
 		if (fio->bufs[n])

Quoted 2 lines · Thomas Gleixner

From: Thomas Gleixner <[email protected]>

Quoted 5 lines

The allocation of the reed solomon control structure can fail, but fec_alloc_bufs() ignores that and subsequent operations in dm verity use the potential NULL pointer unconditionally.

Add a proper check and abort if init_rs() fails.

This changelog makes little sense: init_rs() isn't in play relative to this patch.

And it runs counter to this commit's changelog:

commit 34c96507e8f6be497c15497be05f489fb34c5880

Author: NeilBrown <[email protected]>
Date:   Mon Apr 10 12:13:00 2017 +1000

dm verity fec: fix GFP flags used with mempool_alloc()

mempool_alloc() cannot fail for GFP_NOIO allocation, so there is no point testing for failure.

One place the code tested for failure was passing "0" as the GFP flags. This is most unusual and is probably meant to be GFP_NOIO, so that is changed.

Also, allocation from ->extra_pool and ->prealloc_pool are repeated before releasing the previous allocation. This can deadlock if the code is servicing a write under high memory pressure. To avoid deadlocks, change these to use GFP_NOWAIT and leave the error handling in place.

Signed-off-by NeilBrown <[email protected]>

Signed-off-by Mike Snitzer <[email protected]>

Seems there is no real need for this patch. Neil, what do you think?

Quoted 5 lines · Mike Snitzer

Quoted 2 lines · Thomas Gleixner

From: Thomas Gleixner <[email protected]>

Quoted 8 lines

Quoted 5 lines

The allocation of the reed solomon control structure can fail, but fec_alloc_bufs() ignores that and subsequent operations in dm verity use the potential NULL pointer unconditionally.

Add a proper check and abort if init_rs() fails.

This changelog makes little sense: init_rs() isn't in play relative to this patch.

	fio->rs = mempool_alloc(v->fec->rs_pool, GFP_NOIO);

        f->rs_pool = mempool_create(num_online_cpus(), fec_rs_alloc,
                                    fec_rs_free, (void *) v);

static void *fec_rs_alloc(gfp_t gfp_mask, void *pool_data)

{
	struct dm_verity *v = (struct dm_verity *)pool_data;

        return init_rs(8, 0x11d, 0, 1, v->fec->roots);
}

So init_rs() is part of the chain, right?

Yes. I missed the NOIO part. But....

Quoted 24 lines

And it runs counter to this commit's changelog:

commit 34c96507e8f6be497c15497be05f489fb34c5880

Author: NeilBrown <[email protected]>
Date:   Mon Apr 10 12:13:00 2017 +1000

dm verity fec: fix GFP flags used with mempool_alloc()

mempool_alloc() cannot fail for GFP_NOIO allocation, so there is no point testing for failure.

One place the code tested for failure was passing "0" as the GFP flags. This is most unusual and is probably meant to be GFP_NOIO, so that is changed.

Also, allocation from ->extra_pool and ->prealloc_pool are repeated before releasing the previous allocation. This can deadlock if the code is servicing a write under high memory pressure. To avoid deadlocks, change these to use GFP_NOWAIT and leave the error handling in place.

Signed-off-by NeilBrown <[email protected]>

Signed-off-by Mike Snitzer <[email protected]>

Seems there is no real need for this patch. Neil, what do you think?

The analysis above forgot to look at the mempool->alloc() callback. So yes, while the NOIO is good at the mempool level, but init_rs() uses GPF_KERNEL so there might be a different can of wurms lurking.

Quoted 3 lines · Thomas Gleixner

The analysis above forgot to look at the mempool->alloc() callback. So yes, while the NOIO is good at the mempool level, but init_rs() uses GPF_KERNEL so there might be a different can of wurms lurking.

The ->alloc call back is not relevant to the question of when mempool_alloc() can return NULL.
If the ->alloc() callback returns a non-NULL value, it will be returned by mempool_alloc().
If it returns NULL, that will not be returned.

mempool_alloc() *only* returns NULL in one place:

	if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
		spin_unlock_irqrestore(&pool->lock, flags);
		return NULL;
	}

so a NULL return is purely dependent on the GFP flags passed. GFP_NOIO contains __GFP_DIRECT_RECLAIM, so NULL cannot be returned.

It seems quite broken that init_rs() uses GFP_KERNEL. It should take a gfp_t arg for the allocation.

If the mempool_alloc() above really needs GFP_NOIO, then it could theoretically deadlock as it performs a GFP_KERNEL allocation inside rs_init(). So in that sense, the code is not correct as-is. It could possibly be fixed by calling memalloc_noio_save() / memalloc_noio_restore() around the call to init_rs() in fec_rs_alloc().

Kees tried to get rid of the Variable Length Arrays in the Reed-Solomon library by replacing them with fixed length arrays on stack. Though they are rather large and Andrew did not fall in love with that solution.

This series addresses that in a different way by splitting the rs control structure up, so that each invocation of rs_init() returns a new instance in which the decoder buffers are allocated. The polynom tables which build the base for the RS codecs are still shareable between the instances to avoid large allocations and initializations of the same data over and over.

The usage sites have been audited and fixed up where necessary to accomodate the decoder change which forbids parallel decoder invocation for a particular rs control instance to prevent buffer corruption.

While at it the patch set tidies up the code and converts the related files over to use SPDX license identifiers.

Changes since V1:

Simplify error path in the diskonchip code and use the proper function to free the decoder.

As this spawns multiple subsystems it should either go through Andrews tree or Kees can route it with his other hardening stuff.