afs: Increase buffer size in afs_update_volume_status()

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@aladdin.ru>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20240211150442.3416-1-d.dulov@aladdin.ru/
Link: https://lore.kernel.org/r/20240212083347.10742-1-d.dulov@aladdin.ru/
Link: https://lore.kernel.org/r/20240219143906.138346-3-dhowells@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index 020ecd4..af3a3f5 100644 (file)
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -353,7 +353,7 @@ 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("");
@@ -361,7 +361,7 @@ 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)) {