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FAILED: patch "[PATCH] dm integrity: fix memory corruption when tag_size is less" failed to apply to 4.19-stable tree

PATCH [email protected] 2 participants 3 messages Apr 18, 2022 – Apr 21, 2022

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[email protected]

author maintainer
#0 lore raw

The patch below does not apply to the 4.19-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 08c1af8f1c13bbf210f1760132f4df24d0ed46d6 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <[email protected]>
Date: Sun, 3 Apr 2022 14:38:22 -0400
Subject: [PATCH] dm integrity: fix memory corruption when tag_size is less
than digest size

It is possible to set up dm-integrity in such a way that the "tag_size" parameter is less than the actual digest size. In this situation, a part of the digest beyond tag_size is ignored.

In this case, dm-integrity would write beyond the end of the ic->recalc_tags array and corrupt memory. The corruption happened in integrity_recalc->integrity_sector_checksum->crypto_shash_final.

Fix this corruption by increasing the tags array so that it has enough padding at the end to accomodate the loop in integrity_recalc() being able to write a full digest size for the last member of the tags array.

Cc [email protected] # v4.19+
Signed-off-by Mikulas Patocka <[email protected]>
Signed-off-by Mike Snitzer <[email protected]>
drivers/md/dm-integrity.c +5 -2
index ad2d5faa2ebb..36ae30b73a6e 100644
@@ -4399,6 +4399,7 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	}
 
 	if (ic->internal_hash) {
+		size_t recalc_tags_size;
 		ic->recalc_wq = alloc_workqueue("dm-integrity-recalc", WQ_MEM_RECLAIM, 1);
 		if (!ic->recalc_wq ) {
 			ti->error = "Cannot allocate workqueue";

@@ -4412,8 +4413,10 @@ static int dm_integrity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 			r = -ENOMEM;
 			goto bad;
 		}
-		ic->recalc_tags = kvmalloc_array(RECALC_SECTORS >> ic->sb->log2_sectors_per_block,
-						 ic->tag_size, GFP_KERNEL);
+		recalc_tags_size = (RECALC_SECTORS >> ic->sb->log2_sectors_per_block) * ic->tag_size;
+		if (crypto_shash_digestsize(ic->internal_hash) > ic->tag_size)
+			recalc_tags_size += crypto_shash_digestsize(ic->internal_hash) - ic->tag_size;
+		ic->recalc_tags = kvmalloc(recalc_tags_size, GFP_KERNEL);
 		if (!ic->recalc_tags) {
 			ti->error = "Cannot allocate tags for recalculating";
 			r = -ENOMEM;
maintainer
#1 lore raw

Hi

Here I'm sending a backport of the patch 08c1af8f1c13bbf210f1760132f4df24d0ed46d6 for the kernel 4.19.

Mikulas

Quoted 9 lines · On Mon, 18 Apr 2022, [email protected] wrote:

The patch below does not apply to the 4.19-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

It is possible to set up dm-integrity in such a way that the "tag_size" parameter is less than the actual digest size. In this situation, a part of the digest beyond tag_size is ignored.

In this case, dm-integrity would write beyond the end of the ic->recalc_tags array and corrupt memory. The corruption happened in integrity_recalc->integrity_sector_checksum->crypto_shash_final.

Fix this corruption by increasing the tags array so that it has enough padding at the end to accomodate the loop in integrity_recalc() being able to write a full digest size for the last member of the tags array.

Cc [email protected] # v4.19+
Signed-off-by Mikulas Patocka <[email protected]>
Signed-off-by Mike Snitzer <[email protected]>
---
 drivers/md/dm-integrity.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
drivers/md/dm-integrity.c +5 -2
Index: linux-stable/drivers/md/dm-integrity.c
===================================================================
@@ -3504,6 +3504,7 @@ try_smaller_buffer:
 	}
 
 	if (ic->sb->flags & cpu_to_le32(SB_FLAG_RECALCULATING)) {
+		size_t recalc_tags_size;
 		if (!ic->internal_hash) {
 			r = -EINVAL;
 			ti->error = "Recalculate is only valid with internal hash";

@@ -3522,8 +3523,10 @@ try_smaller_buffer:
 			r = -ENOMEM;
 			goto bad;
 		}
-		ic->recalc_tags = kvmalloc_array(RECALC_SECTORS >> ic->sb->log2_sectors_per_block,
-						 ic->tag_size, GFP_KERNEL);
+		recalc_tags_size = (RECALC_SECTORS >> ic->sb->log2_sectors_per_block) * ic->tag_size;
+		if (crypto_shash_digestsize(ic->internal_hash) > ic->tag_size)
+			recalc_tags_size += crypto_shash_digestsize(ic->internal_hash) - ic->tag_size;
+		ic->recalc_tags = kvmalloc(recalc_tags_size, GFP_KERNEL);
 		if (!ic->recalc_tags) {
 			ti->error = "Cannot allocate tags for recalculating";
 			r = -ENOMEM;
author maintainer
#2 lore raw
Quoted 4 lines · Mikulas Patocka

Hi

Here I'm sending a backport of the patch 08c1af8f1c13bbf210f1760132f4df24d0ed46d6 for the kernel 4.19.

Now queued up, thanks.

greg k-h