Patch "scsi: sd: Fix capacity calculation with 32-bit sector_t" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

scsi: sd: Fix capacity calculation with 32-bit sector_t

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
scsi-sd-fix-capacity-calculation-with-32-bit-sector_t.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Martin K. Petersen" <[email protected]>
Date: Tue, 4 Apr 2017 10:42:30 -0400
Subject: scsi: sd: Fix capacity calculation with 32-bit sector_t

From: Martin K. Petersen <[email protected]>

commit 7c856152cb92f8eee2df29ef325a1b1f43161aff upstream.

We previously made sure that the reported disk capacity was less than 0xffffffff blocks when the kernel was not compiled with large sector_t support (CONFIG_LBDAF). However, this check assumed that the capacity was reported in units of 512 bytes.

Add a sanity check function to ensure that we only enable disks if the entire reported capacity can be expressed in terms of sector_t.

---
 drivers/scsi/sd.c |   20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

@@ -2057,6 +2057,22 @@ static void read_capacity_error(struct s
 
 #define READ_CAPACITY_RETRIES_ON_RESET	10
 
+/*
+ * Ensure that we don't overflow sector_t when CONFIG_LBDAF is not set
+ * and the reported logical block size is bigger than 512 bytes. Note
+ * that last_sector is a u64 and therefore logical_to_sectors() is not
+ * applicable.
+ */
+static bool sd_addressable_capacity(u64 lba, unsigned int sector_size)
+{
+	u64 last_sector = (lba + 1ULL) << (ilog2(sector_size) - 9);
+
+	if (sizeof(sector_t) == 4 && last_sector > U32_MAX)
+		return false;
+
+	return true;
+}
+
 static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp,
 						unsigned char *buffer)
 {

@@ -2122,7 +2138,7 @@ static int read_capacity_16(struct scsi_
 		return -ENODEV;
 	}
 
-	if ((sizeof(sdkp->capacity) == 4) && (lba >= 0xffffffffULL)) {
+	if (!sd_addressable_capacity(lba, sector_size)) {
 		sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use a "
 			"kernel compiled with support for large block "
 			"devices.\n");

@@ -2208,7 +2224,7 @@ static int read_capacity_10(struct scsi_
 		return sector_size;
 	}
 
-	if ((sizeof(sdkp->capacity) == 4) && (lba == 0xffffffff)) {
+	if (!sd_addressable_capacity(lba, sector_size)) {
 		sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use a "
 			"kernel compiled with support for large block "
 			"devices.\n");

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/scsi-sd-consider-max_xfer_blocks-if-opt_xfer_blocks-is-unusable.patch queue-4.9/scsi-qla2xxx-add-fix-to-read-correct-register-value-for-isp82xx.patch queue-4.9/scsi-sr-sanity-check-returned-mode-data.patch queue-4.9/scsi-sd-fix-capacity-calculation-with-32-bit-sector_t.patch