[SRU][M/J][PATCH 1/1] afs: Increase buffer size in afs_update_volume_status()

[Bethany Jamison]

From: Daniil Dulov <d.dulov at aladdin.ru>

[ Upstream commit 6ea38e2aeb72349cad50e38899b0ba6fbcb2af3d ]

The max length of volume->vid value is 20 characters.
So increase idbuf[] size up to 24 to avoid overflow.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

[DH: Actually, it's 20 + NUL, so increase it to 24 and use snprintf()]

Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation")
Signed-off-by: Daniil Dulov <d.dulov at aladdin.ru>
Signed-off-by: David Howells <dhowells at redhat.com>
Link: https://lore.kernel.org/r/20240211150442.3416-1-d.dulov@aladdin.ru/ # v1
Link: https://lore.kernel.org/r/20240212083347.10742-1-d.dulov@aladdin.ru/ # v2
Link: https://lore.kernel.org/r/20240219143906.138346-3-dhowells@redhat.com
Signed-off-by: Christian Brauner <brauner at kernel.org>
Signed-off-by: Sasha Levin <sashal at kernel.org>
(cherry picked from commit 6e6065dd25b661420fac19c34282b6c626fcd35e linux-6.6.y)
CVE-2024-26736
Signed-off-by: Bethany Jamison <bethany.jamison at canonical.com>
---
 fs/afs/volume.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index 115c081a8e2ce..c028598a903c9 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -337,7 +337,7 @@ static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
 {
 	struct afs_server_list *new, *old, *discard;
 	struct afs_vldb_entry *vldb;
-	char idbuf[16];
+	char idbuf[24];
 	int ret, idsz;
 
 	_enter("");
@@ -345,7 +345,7 @@ static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
 	/* We look up an ID by passing it as a decimal string in the
 	 * operation's name parameter.
 	 */
-	idsz = sprintf(idbuf, "%llu", volume->vid);
+	idsz = snprintf(idbuf, sizeof(idbuf), "%llu", volume->vid);
 
 	vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
 	if (IS_ERR(vldb)) {
-- 
2.34.1