diff options
| author | Andrii Nakryiko <andrii@kernel.org> | 2020-10-14 13:45:28 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-14 14:54:45 -0700 |
| commit | 09cad07547445bf3a41683e4d3abcd154c123ef5 (patch) | |
| tree | 87c5446a685d3ab5db6e91d869a6726960e892b3 /kernel | |
| parent | 4da9af0014b51c8b015ed8c622440ef28912efe6 (diff) | |
fs: fix NULL dereference due to data race in prepend_path()
Fix data race in prepend_path() with re-reading mnt->mnt_ns twice
without holding the lock.
is_mounted() does check for NULL, but is_anon_ns(mnt->mnt_ns) might
re-read the pointer again which could be NULL already, if in between
reads one of kern_unmount()/kern_unmount_array()/umount_tree() sets
mnt->mnt_ns to NULL.
This is seen in production with the following stack trace:
BUG: kernel NULL pointer dereference, address: 0000000000000048
...
RIP: 0010:prepend_path.isra.4+0x1ce/0x2e0
Call Trace:
d_path+0xe6/0x150
proc_pid_readlink+0x8f/0x100
vfs_readlink+0xf8/0x110
do_readlinkat+0xfd/0x120
__x64_sys_readlinkat+0x1a/0x20
do_syscall_64+0x42/0x110
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: f2683bd8d5bd ("[PATCH] fix d_absolute_path() interplay with fsmount()")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
0 files changed, 0 insertions, 0 deletions