linux/fs/fuse
Greg Kurz d92d88f056 fuse: Fix crash in fuse_dentry_automount() error path
If fuse_fill_super_submount() returns an error, the error path
triggers a crash:

[   26.206673] BUG: kernel NULL pointer dereference, address: 0000000000000000
[...]
[   26.226362] RIP: 0010:__list_del_entry_valid+0x25/0x90
[...]
[   26.247938] Call Trace:
[   26.248300]  fuse_mount_remove+0x2c/0x70 [fuse]
[   26.248892]  virtio_kill_sb+0x22/0x160 [virtiofs]
[   26.249487]  deactivate_locked_super+0x36/0xa0
[   26.250077]  fuse_dentry_automount+0x178/0x1a0 [fuse]

The crash happens because fuse_mount_remove() assumes that the FUSE
mount was already added to list under the FUSE connection, but this
only done after fuse_fill_super_submount() has returned success.

This means that until fuse_fill_super_submount() has returned success,
the FUSE mount isn't actually owned by the superblock. We should thus
reclaim ownership by clearing sb->s_fs_info, which will skip the call
to fuse_mount_remove(), and perform rollback, like virtio_fs_get_tree()
already does for the root sb.

Fixes: bf109c6404 ("fuse: implement crossmounts")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2021-06-09 15:33:40 +02:00
..
acl.c fuse: add a flag FUSE_SETXATTR_ACL_KILL_SGID to kill SGID 2021-04-14 10:40:57 +02:00
control.c fuse: split fuse_mount off of fuse_conn 2020-09-18 15:17:41 +02:00
cuse.c cuse: simplify refcount 2021-04-14 10:40:58 +02:00
dax.c fuse: split fuse_mount off of fuse_conn 2020-09-18 15:17:41 +02:00
dev.c fuse: fix matching of FUSE_DEV_IOC_CLONE command 2021-04-14 10:40:57 +02:00
dir.c fuse: Fix crash in fuse_dentry_automount() error path 2021-06-09 15:33:40 +02:00
file.c fuse update for 5.13 2021-04-30 15:23:16 -07:00
fuse_i.h fuse update for 5.13 2021-04-30 15:23:16 -07:00
inode.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-05-02 09:14:01 -07:00
ioctl.c fuse: convert to fileattr 2021-04-12 15:04:30 +02:00
Kconfig virtiofs: implement dax read/write operations 2020-09-10 11:39:23 +02:00
Makefile fuse: move ioctl to separate source file 2021-04-12 15:04:30 +02:00
readdir.c new helper: inode_wrong_type() 2021-03-08 10:19:35 -05:00
virtio_fs.c virtiofs: fix userns 2021-04-14 10:40:58 +02:00
xattr.c fuse: extend FUSE_SETXATTR request 2021-04-14 10:40:57 +02:00