linux-kernel - [PATCH] fcntl: don't leak fd reference when fixup_compat

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Date:   Tue, 14 Nov 2017 15:24:31 -0500
From:   Jeff Layton <jlayton@...nel.org>
To:     linux-fsdevel@...r.kernel.org
Cc:     Vitaly Lipatov <lav@...rsoft.ru>, hch@....de, bfields@...ldses.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] fcntl: don't leak fd reference when fixup_compat_flock fails

From: Jeff Layton <jlayton@...hat.com>

Currently we just return err here, but we need to put the fd reference
first.

Fixes: 94073ad77fff (fs/locks: don't mess with the address limit in compat_fcntl64)
Signed-off-by: Jeff Layton <jlayton@...hat.com>
---
 fs/fcntl.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

I don't have a great way to test this. There's another similar bug in
the F_GETLK64 case as well, but Vitaly is looking at another problem
there.

diff --git a/fs/fcntl.c b/fs/fcntl.c
index e44a95dd3f86..0793eca4d0ec 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -632,9 +632,8 @@ COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 		if (err)
 			break;
 		err = fixup_compat_flock(&flock);
-		if (err)
-			return err;
-		err = put_compat_flock(&flock, compat_ptr(arg));
+		if (!err)
+			err = put_compat_flock(&flock, compat_ptr(arg));
 		break;
 	case F_GETLK64:
 	case F_OFD_GETLK:
-- 
2.14.3