linux-kernel - [PATCH resend] 9p: fix a potential acl leak

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Message-Id: <1486678332-2430-1-git-send-email-xiyou.wangcong@gmail.com>
Date:   Thu,  9 Feb 2017 14:12:12 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        Eric Van Hensbergen <ericvh@...il.com>,
        Ron Minnich <rminnich@...dia.gov>,
        Latchesar Ionkov <lucho@...kov.net>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH resend] 9p: fix a potential acl leak

posix_acl_update_mode() could possibly clear 'acl', if so
we leak the memory pointed by 'acl'. Save this pointer
before calling posix_acl_update_mode() and release the memory
if 'acl' really gets cleared.

Reported-by: Mark Salyzyn <salyzyn@...roid.com>
Reviewed-by: Jan Kara <jack@...e.cz>
Reviewed-by: Greg Kurz <groug@...d.org>
Cc: Eric Van Hensbergen <ericvh@...il.com>
Cc: Ron Minnich <rminnich@...dia.gov>
Cc: Latchesar Ionkov <lucho@...kov.net>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 fs/9p/acl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/9p/acl.c b/fs/9p/acl.c
index b3c2cc7..082d227 100644
--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -277,6 +277,7 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
 	case ACL_TYPE_ACCESS:
 		if (acl) {
 			struct iattr iattr;
+			struct posix_acl *old_acl = acl;
 
 			retval = posix_acl_update_mode(inode, &iattr.ia_mode, &acl);
 			if (retval)
@@ -287,6 +288,7 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
 				 * by the mode bits. So don't
 				 * update ACL.
 				 */
+				posix_acl_release(old_acl);
 				value = NULL;
 				size = 0;
 			}
-- 
2.5.5