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| author | Zhihao Cheng <chengzhihao1@huawei.com> | 2023-05-16 17:16:19 +0300 |
|---|---|---|
| committer | Amir Goldstein <amir73il@gmail.com> | 2023-06-19 14:01:12 +0300 |
| commit | f4e19e595cc2e76a8a58413eb19d3d9c51328b53 (patch) | |
| tree | 85b5d99d417d43fc528f6ea1178ac9d997398cd4 /fs | |
| parent | 1a73f5b8f079fd42a544c1600beface50c63af7c (diff) | |
| download | linux-f4e19e595cc2e76a8a58413eb19d3d9c51328b53.tar.xz | |
ovl: fix null pointer dereference in ovl_get_acl_rcu()
Following process:
P1 P2
path_openat
link_path_walk
may_lookup
inode_permission(rcu)
ovl_permission
acl_permission_check
check_acl
get_cached_acl_rcu
ovl_get_inode_acl
realinode = ovl_inode_real(ovl_inode)
drop_cache
__dentry_kill(ovl_dentry)
iput(ovl_inode)
ovl_destroy_inode(ovl_inode)
dput(oi->__upperdentry)
dentry_kill(upperdentry)
dentry_unlink_inode
upperdentry->d_inode = NULL
ovl_inode_upper
upperdentry = ovl_i_dentry_upper(ovl_inode)
d_inode(upperdentry) // returns NULL
IS_POSIXACL(realinode) // NULL pointer dereference
, will trigger an null pointer dereference at realinode:
[ 205.472797] BUG: kernel NULL pointer dereference, address:
0000000000000028
[ 205.476701] CPU: 2 PID: 2713 Comm: ls Not tainted
6.3.0-12064-g2edfa098e750-dirty #1216
[ 205.478754] RIP: 0010:do_ovl_get_acl+0x5d/0x300
[ 205.489584] Call Trace:
[ 205.489812] <TASK>
[ 205.490014] ovl_get_inode_acl+0x26/0x30
[ 205.490466] get_cached_acl_rcu+0x61/0xa0
[ 205.490908] generic_permission+0x1bf/0x4e0
[ 205.491447] ovl_permission+0x79/0x1b0
[ 205.491917] inode_permission+0x15e/0x2c0
[ 205.492425] link_path_walk+0x115/0x550
[ 205.493311] path_lookupat.isra.0+0xb2/0x200
[ 205.493803] filename_lookup+0xda/0x240
[ 205.495747] vfs_fstatat+0x7b/0xb0
Fetch a reproducer in [Link].
Use the helper ovl_i_path_realinode() to get realinode and then do
non-nullptr checking.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217404
Fixes: 332f606b32b6 ("ovl: enable RCU'd ->get_acl()")
Cc: <stable@vger.kernel.org> # v5.15
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Suggested-by: Christian Brauner <brauner@kernel.org>
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/overlayfs/inode.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index ca56b1328a2c..e7e888dea634 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -558,20 +558,20 @@ struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap, struct inode *inode, int type, bool rcu, bool noperm) { - struct inode *realinode = ovl_inode_real(inode); + struct inode *realinode; struct posix_acl *acl; struct path realpath; - if (!IS_POSIXACL(realinode)) - return NULL; - /* Careful in RCU walk mode */ - ovl_i_path_real(inode, &realpath); - if (!realpath.dentry) { + realinode = ovl_i_path_real(inode, &realpath); + if (!realinode) { WARN_ON(!rcu); return ERR_PTR(-ECHILD); } + if (!IS_POSIXACL(realinode)) + return NULL; + if (rcu) { /* * If the layer is idmapped drop out of RCU path walk |