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From: Andy Lutomirski <luto@amacapital.net>
Date: Wed, 8 Oct 2014 12:37:46 -0700
Subject: [PATCH] fs: Add a missing permission check to do_umount
Accessing do_remount_sb should require global CAP_SYS_ADMIN, but
only one of the two call sites was appropriately protected.
Fixes CVE-2014-7975.
Cc: stable@vger.kernel.org
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
---
fs/namespace.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/namespace.c b/fs/namespace.c
index c8e3034ff4b2..fbba8b17330d 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1439,6 +1439,8 @@ static int do_umount(struct mount *mnt, int flags)
* Special case for "unmounting" root ...
* we just try to remount it readonly.
*/
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
down_write(&sb->s_umount);
if (!(sb->s_flags & MS_RDONLY))
retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
--
1.9.3
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