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FAILED: patch "[PATCH] crypto: skcipher - Unmap pages after an external error" failed to apply to 4.4-stable tree

PATCH [email protected] 1 participant 1 message Oct 8, 2019

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The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0ba3c026e685573bd3534c17e27da7c505ac99c4 Mon Sep 17 00:00:00 2001
From: Herbert Xu <[email protected]>
Date: Fri, 6 Sep 2019 13:13:06 +1000
Subject: [PATCH] crypto: skcipher - Unmap pages after an external error

skcipher_walk_done may be called with an error by internal or external callers. For those internal callers we shouldn't unmap pages but for external callers we must unmap any pages that are in use.

This patch distinguishes between the two cases by checking whether walk->nbytes is zero or not. For internal callers, we now set walk->nbytes to zero prior to the call. For external callers, walk->nbytes has always been non-zero (as zero is used to indicate the termination of a walk).

Reported-by Ard Biesheuvel <[email protected]>
Fixes 5cde0af2a982 ("[CRYPTO] cipher: Added block cipher type")
Cc <[email protected]>
Signed-off-by Herbert Xu <[email protected]>
Tested-by Ard Biesheuvel <[email protected]>
Signed-off-by Herbert Xu <[email protected]>
crypto/skcipher.c +23 -19
index 5d836fc3df3e..22753c1c7202 100644
@@ -90,7 +90,7 @@ static inline u8 *skcipher_get_spot(u8 *start, unsigned int len)
 	return max(start, end_page);
 }
 
-static void skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize)
+static int skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize)
 {
 	u8 *addr;
 

@@ -98,19 +98,21 @@ static void skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize)
 	addr = skcipher_get_spot(addr, bsize);
 	scatterwalk_copychunks(addr, &walk->out, bsize,
 			       (walk->flags & SKCIPHER_WALK_PHYS) ? 2 : 1);
+	return 0;
 }
 
 int skcipher_walk_done(struct skcipher_walk *walk, int err)
 {
-	unsigned int n; /* bytes processed */
-	bool more;
+	unsigned int n = walk->nbytes;
+	unsigned int nbytes = 0;
 
-	if (unlikely(err < 0))
+	if (!n)
 		goto finish;
 
-	n = walk->nbytes - err;
-	walk->total -= n;
-	more = (walk->total != 0);
+	if (likely(err >= 0)) {
+		n -= err;
+		nbytes = walk->total - n;
+	}
 
 	if (likely(!(walk->flags & (SKCIPHER_WALK_PHYS |
 				    SKCIPHER_WALK_SLOW |

@@ -126,7 +128,7 @@ int skcipher_walk_done(struct skcipher_walk *walk, int err)
 		memcpy(walk->dst.virt.addr, walk->page, n);
 		skcipher_unmap_dst(walk);
 	} else if (unlikely(walk->flags & SKCIPHER_WALK_SLOW)) {
-		if (err) {
+		if (err > 0) {
 			/*
 			 * Didn't process all bytes.  Either the algorithm is
 			 * broken, or this was the last step and it turned out

@@ -134,27 +136,29 @@ int skcipher_walk_done(struct skcipher_walk *walk, int err)
 			 * the algorithm requires it.
 			 */
 			err = -EINVAL;
-			goto finish;
-		}
-		skcipher_done_slow(walk, n);
-		goto already_advanced;
+			nbytes = 0;
+		} else
+			n = skcipher_done_slow(walk, n);
 	}
 
+	if (err > 0)
+		err = 0;
+
+	walk->total = nbytes;
+	walk->nbytes = 0;
+
 	scatterwalk_advance(&walk->in, n);
 	scatterwalk_advance(&walk->out, n);
-already_advanced:
-	scatterwalk_done(&walk->in, 0, more);
-	scatterwalk_done(&walk->out, 1, more);
+	scatterwalk_done(&walk->in, 0, nbytes);
+	scatterwalk_done(&walk->out, 1, nbytes);
 
-	if (more) {
+	if (nbytes) {
 		crypto_yield(walk->flags & SKCIPHER_WALK_SLEEP ?
 			     CRYPTO_TFM_REQ_MAY_SLEEP : 0);
 		return skcipher_walk_next(walk);
 	}
-	err = 0;
-finish:
-	walk->nbytes = 0;
 
+finish:
 	/* Short-circuit for the common/fast path. */
 	if (!((unsigned long)walk->buffer | (unsigned long)walk->page))
 		goto out;