+ fsnotify-dont-put-user-context-if-it-was-never-assigned.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: fsnotify: don't put user context if it was never assigned
has been added to the -mm tree.  Its filename is
     fsnotify-dont-put-user-context-if-it-was-never-assigned.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/fsnotify-dont-put-user-context-if-it-was-never-assigned.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/fsnotify-dont-put-user-context-if-it-was-never-assigned.patch

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------------------------------------------------------
From: Sasha Levin <sasha.levin@oracle.com>
Subject: 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.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/notify/inotify/inotify_fsnotify.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff -puN fs/notify/inotify/inotify_fsnotify.c~fsnotify-dont-put-user-context-if-it-was-never-assigned fs/notify/inotify/inotify_fsnotify.c
--- a/fs/notify/inotify/inotify_fsnotify.c~fsnotify-dont-put-user-context-if-it-was-never-assigned
+++ a/fs/notify/inotify/inotify_fsnotify.c
@@ -165,8 +165,10 @@ static void inotify_free_group_priv(stru
 	/* 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)
_

Patches currently in -mm which might be from sasha.levin@oracle.com are

mm-mmap-use-pr_emerg-when-printing-bug-related-information.patch
fs-notify-groupc-make-fsnotify_final_destroy_group-static.patch
fsnotify-dont-put-user-context-if-it-was-never-assigned.patch
mm-balloon_compaction-ignore-anonymous-pages.patch
introduce-dump_vma.patch
introduce-dump_vma-fix.patch
introduce-dump_vma-fix-2.patch
introduce-vm_bug_on_vma.patch
convert-a-few-vm_bug_on-callers-to-vm_bug_on_vma.patch
convert-a-few-vm_bug_on-callers-to-vm_bug_on_vma-checkpatch-fixes.patch
mm-mmapc-clean-up-config_debug_vm_rb-checks.patch
vmstat-on-demand-vmstat-workers-v8-fix-2.patch
mm-introduce-do_shared_fault-and-drop-do_fault-fix-fix.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
mm-replace-remap_file_pages-syscall-with-emulation.patch