Hi.

Here I'm sending the patch backported for the kernel 4.14.

Mikulas

From gregkh@linuxfoundation.org Mon Apr 15 12:38:03 2019

Date: Mon, 15 Apr 2019 18:37:16 +0200 From: gregkh@linuxfoundation.org To: mpatocka@redhat.com, snitzer@redhat.com Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] dm integrity: change memcmp to strncmp in dm_integrity_ctr" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-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 stable@vger.kernel.org.

thanks,

greg k-h

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

From 0d74e6a3b6421d98eeafbed26f29156d469bc0b5 Mon Sep 17 00:00:00 2001

From: Mikulas Patocka mpatocka@redhat.com Date: Wed, 13 Mar 2019 07:56:02 -0400 Subject: [PATCH] dm integrity: change memcmp to strncmp in dm_integrity_ctr

If the string opt_string is small, the function memcmp can access bytes that are beyond the terminating nul character. In theory, it could cause segfault, if opt_string were located just below some unmapped memory.

Change from memcmp to strncmp so that we don't read bytes beyond the end of the string.

Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Mikulas Patocka mpatocka@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com

--- drivers/md/dm-integrity.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

Index: linux-stable/drivers/md/dm-integrity.c =================================================================== --- linux-stable.orig/drivers/md/dm-integrity.c 2019-04-16 10:41:05.000000000 +0200 +++ linux-stable/drivers/md/dm-integrity.c 2019-04-16 10:41:05.000000000 +0200 @@ -2889,17 +2889,17 @@ static int dm_integrity_ctr(struct dm_ta goto bad; } ic->sectors_per_block = val >> SECTOR_SHIFT; - } else if (!memcmp(opt_string, "internal_hash:", strlen("internal_hash:"))) { + } else if (!strncmp(opt_string, "internal_hash:", strlen("internal_hash:"))) { r = get_alg_and_key(opt_string, &ic->internal_hash_alg, &ti->error, "Invalid internal_hash argument"); if (r) goto bad; - } else if (!memcmp(opt_string, "journal_crypt:", strlen("journal_crypt:"))) { + } else if (!strncmp(opt_string, "journal_crypt:", strlen("journal_crypt:"))) { r = get_alg_and_key(opt_string, &ic->journal_crypt_alg, &ti->error, "Invalid journal_crypt argument"); if (r) goto bad; - } else if (!memcmp(opt_string, "journal_mac:", strlen("journal_mac:"))) { + } else if (!strncmp(opt_string, "journal_mac:", strlen("journal_mac:"))) { r = get_alg_and_key(opt_string, &ic->journal_mac_alg, &ti->error, "Invalid journal_mac argument"); if (r)