From: Daniel Vogelbacher Date: Sun, 1 Feb 2026 08:34:01 +0000 (+0100) Subject: ceph: fix oops due to invalid pointer for kfree() in parse_longname() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bc8dedae022ce3058659c3addef3ec4b41d15e00;p=thirdparty%2Fkernel%2Flinux.git ceph: fix oops due to invalid pointer for kfree() in parse_longname() This fixes a kernel oops when reading ceph snapshot directories (.snap), for example by simply running `ls /mnt/my_ceph/.snap`. The variable str is guarded by __free(kfree), but advanced by one for skipping the initial '_' in snapshot names. Thus, kfree() is called with an invalid pointer. This patch removes the need for advancing the pointer so kfree() is called with correct memory pointer. Steps to reproduce: 1. Create snapshots on a cephfs volume (I've 63 snaps in my testcase) 2. Add cephfs mount to fstab $ echo "samba-fileserver@.files=/volumes/datapool/stuff/3461082b-ecc9-4e82-8549-3fd2590d3fb6 /mnt/test/stuff ceph acl,noatime,_netdev 0 0" >> /etc/fstab 3. Reboot the system $ systemctl reboot 4. Check if it's really mounted $ mount | grep stuff 5. List snapshots (expected 63 snapshots on my system) $ ls /mnt/test/stuff/.snap Now ls hangs forever and the kernel log shows the oops. Cc: stable@vger.kernel.org Fixes: 101841c38346 ("[ceph] parse_longname(): strrchr() expects NUL-terminated string") Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220807 Suggested-by: Helge Deller Signed-off-by: Daniel Vogelbacher Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov --- diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c index 0ea4db650f85..9a115282f67d 100644 --- a/fs/ceph/crypto.c +++ b/fs/ceph/crypto.c @@ -166,12 +166,13 @@ static struct inode *parse_longname(const struct inode *parent, struct ceph_vino vino = { .snap = CEPH_NOSNAP }; char *name_end, *inode_number; int ret = -EIO; - /* NUL-terminate */ - char *str __free(kfree) = kmemdup_nul(name, *name_len, GFP_KERNEL); + /* Snapshot name must start with an underscore */ + if (*name_len <= 0 || name[0] != '_') + return ERR_PTR(-EIO); + /* Skip initial '_' and NUL-terminate */ + char *str __free(kfree) = kmemdup_nul(name + 1, *name_len - 1, GFP_KERNEL); if (!str) return ERR_PTR(-ENOMEM); - /* Skip initial '_' */ - str++; name_end = strrchr(str, '_'); if (!name_end) { doutc(cl, "failed to parse long snapshot name: %s\n", str);