diff options
| author | Sasha Levin <sasha.levin@oracle.com> | 2014-10-09 15:24:37 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-10-09 22:25:45 -0400 |
| commit | 105d1b425303120c7681abc0761b6fc6c3f8a8e8 (patch) | |
| tree | dd62771c0fc306feb10074c361bb422b3b634041 /fs/notify | |
| parent | cafbaae8afdb1e6cf9f4715aea2c897cf407ddfd (diff) | |
| download | lwn-105d1b425303120c7681abc0761b6fc6c3f8a8e8.tar.gz lwn-105d1b425303120c7681abc0761b6fc6c3f8a8e8.zip | |
fsnotify: don't put user context if it was never assigned
On some failure paths we may attempt to free user context even if it
wasn't assigned yet. This will cause a NULL ptr deref and a kernel BUG.
The path I was looking at is in inotify_new_group():
oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL);
if (unlikely(!oevent)) {
fsnotify_destroy_group(group);
return ERR_PTR(-ENOMEM);
}
fsnotify_destroy_group() would get called here, but
group->inotify_data.user is only getting assigned later:
group->inotify_data.user = get_current_user();
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rlove@rlove.org>
Cc: Eric Paris <eparis@parisplace.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/notify')
| -rw-r--r-- | fs/notify/inotify/inotify_fsnotify.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c index 0f88bc0b4e6c..7d888d77d59a 100644 --- a/fs/notify/inotify/inotify_fsnotify.c +++ b/fs/notify/inotify/inotify_fsnotify.c @@ -165,8 +165,10 @@ static void inotify_free_group_priv(struct fsnotify_group *group) /* ideally the idr is empty and we won't hit the BUG in the callback */ idr_for_each(&group->inotify_data.idr, idr_callback, group); idr_destroy(&group->inotify_data.idr); - atomic_dec(&group->inotify_data.user->inotify_devs); - free_uid(group->inotify_data.user); + if (group->inotify_data.user) { + atomic_dec(&group->inotify_data.user->inotify_devs); + free_uid(group->inotify_data.user); + } } static void inotify_free_event(struct fsnotify_event *fsn_event) |