[ 078/104] inotify: invalid mask should return a error number but not set it

[Greg Kroah-Hartman]

3.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Zhao Hongjiang <zhaohongjiang@xxxxxxxxxx>

commit 04df32fa10ab9a6f0643db2949d42efc966bc844 upstream.

When we run the crackerjack testsuite, the inotify_add_watch test is
stalled.

This is caused by the invalid mask 0 - the task is waiting for the event
but it never comes.  inotify_add_watch() should return -EINVAL as it did
before commit 676a0675cf92 ("inotify: remove broken mask checks causing
unmount to be EINVAL").  That commit removes the invalid mask check, but
that check is needed.

Check the mask's ALL_INOTIFY_BITS before the inotify_arg_to_mask() call.
If none are set, just return -EINVAL.

Because IN_UNMOUNT is in ALL_INOTIFY_BITS, this change will not trigger
the problem that above commit fixed.

[akpm@xxxxxxxxxxxxxxxxxxxx: fix build]
Signed-off-by: Zhao Hongjiang <zhaohongjiang@xxxxxxxxxx>
Acked-by: Jim Somerville <Jim.Somerville@xxxxxxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Jerome Marchand <jmarchan@xxxxxxxxxx>
Cc: Eric Paris <eparis@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -574,7 +574,6 @@ static int inotify_update_existing_watch
 	int add = (arg & IN_MASK_ADD);
 	int ret;
 
-	/* don't allow invalid bits: we don't want flags set */
 	mask = inotify_arg_to_mask(arg);
 
 	fsn_mark = fsnotify_find_inode_mark(group, inode);
@@ -625,7 +624,6 @@ static int inotify_new_watch(struct fsno
 	struct idr *idr = &group->inotify_data.idr;
 	spinlock_t *idr_lock = &group->inotify_data.idr_lock;
 
-	/* don't allow invalid bits: we don't want flags set */
 	mask = inotify_arg_to_mask(arg);
 
 	tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
@@ -753,6 +751,10 @@ SYSCALL_DEFINE3(inotify_add_watch, int,
 	int ret;
 	unsigned flags = 0;
 
+	/* don't allow invalid bits: we don't want flags set */
+	if (unlikely(!(mask & ALL_INOTIFY_BITS)))
+		return -EINVAL;
+
 	f = fdget(fd);
 	if (unlikely(!f.file))
 		return -EBADF;


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