[patch 084/114] pipe_rdwr_fasync: fix the error handling to prevent the leak/crash

[Greg KH]

2.6.28-stable review patch.  If anyone has any objections, please let us know.

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

From: Oleg Nesterov <oleg@xxxxxxxxxx>

commit e5bc49ba7439b9726006d031d440cba96819f0f8 upstream.

If the second fasync_helper() fails, pipe_rdwr_fasync() returns the error
but leaves the file on ->fasync_readers.

This was always wrong, but since 233e70f4228e78eb2f80dc6650f65d3ae3dbf17c
"saner FASYNC handling on file close" we have the new problem.  Because in
this case setfl() doesn't set FASYNC bit, __fput() will not do
->fasync(0), and we leak fasync_struct with ->fa_file pointing to the
freed file.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/pipe.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -699,12 +699,12 @@ pipe_rdwr_fasync(int fd, struct file *fi
 	int retval;
 
 	mutex_lock(&inode->i_mutex);
-
 	retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
-
-	if (retval >= 0)
+	if (retval >= 0) {
 		retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
-
+		if (retval < 0) /* this can happen only if on == T */
+			fasync_helper(-1, filp, 0, &pipe->fasync_readers);
+	}
 	mutex_unlock(&inode->i_mutex);
 
 	if (retval < 0)


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