diff options
| author | Luis Henriques <lhenriques@suse.com> | 2019-10-25 14:05:24 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-12 19:20:39 +0100 |
| commit | 6f9657793a6eea9d9e1f27b26deda0f77ecc4684 (patch) | |
| tree | da3671d9d0413974748c6afc3e2adf5cc50f8007 /fs/ceph | |
| parent | 3840610d60b2e80bf49dba78d5dd9711cfd2207b (diff) | |
ceph: fix use-after-free in __ceph_remove_cap()
commit ea60ed6fcf29eebc78f2ce91491e6309ee005a01 upstream.
KASAN reports a use-after-free when running xfstest generic/531, with the
following trace:
[ 293.903362] kasan_report+0xe/0x20
[ 293.903365] rb_erase+0x1f/0x790
[ 293.903370] __ceph_remove_cap+0x201/0x370
[ 293.903375] __ceph_remove_caps+0x4b/0x70
[ 293.903380] ceph_evict_inode+0x4e/0x360
[ 293.903386] evict+0x169/0x290
[ 293.903390] __dentry_kill+0x16f/0x250
[ 293.903394] dput+0x1c6/0x440
[ 293.903398] __fput+0x184/0x330
[ 293.903404] task_work_run+0xb9/0xe0
[ 293.903410] exit_to_usermode_loop+0xd3/0xe0
[ 293.903413] do_syscall_64+0x1a0/0x1c0
[ 293.903417] entry_SYSCALL_64_after_hwframe+0x44/0xa9
This happens because __ceph_remove_cap() may queue a cap release
(__ceph_queue_cap_release) which can be scheduled before that cap is
removed from the inode list with
rb_erase(&cap->ci_node, &ci->i_caps);
And, when this finally happens, the use-after-free will occur.
This can be fixed by removing the cap from the inode list before being
removed from the session list, and thus eliminating the risk of an UAF.
Cc: stable@vger.kernel.org
Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/ceph')
| -rw-r--r-- | fs/ceph/caps.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index db547af01b59..4c0b220e20ba 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1053,6 +1053,11 @@ void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release) dout("__ceph_remove_cap %p from %p\n", cap, &ci->vfs_inode); + /* remove from inode's cap rbtree, and clear auth cap */ + rb_erase(&cap->ci_node, &ci->i_caps); + if (ci->i_auth_cap == cap) + ci->i_auth_cap = NULL; + /* remove from session list */ spin_lock(&session->s_cap_lock); if (session->s_cap_iterator == cap) { @@ -1088,11 +1093,6 @@ void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release) spin_unlock(&session->s_cap_lock); - /* remove from inode list */ - rb_erase(&cap->ci_node, &ci->i_caps); - if (ci->i_auth_cap == cap) - ci->i_auth_cap = NULL; - if (removed) ceph_put_cap(mdsc, cap); |