From: Jann Horn <jann@thejh.net>
Date: Fri, 11 Sep 2015 19:39:33 +0000 (+0200)
Subject: xfs: fix type confusion in xfs_ioc_swapext
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=3e0a396546450536679ae4d3bd70290ce0b0c79c;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

xfs: fix type confusion in xfs_ioc_swapext

Without this check, the following XFS_I invocations would return bad
pointers when used on non-XFS inodes (perhaps pointers into preceding
allocator chunks).

This could be used by an attacker to trick xfs_swap_extents into
performing locking operations on attacker-chosen structures in kernel
memory, potentially leading to code execution in the kernel.  (I have
not investigated how likely this is to be usable for an attack in
practice.)

Signed-off-by: Jann Horn <jann@thejh.net>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index dbca7375deef..63a6ff2cfc68 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1575,6 +1575,12 @@ xfs_ioc_swapext(
 		goto out_put_tmp_file;
 	}
 
+	if (f.file->f_op != &xfs_file_operations ||
+	    tmp.file->f_op != &xfs_file_operations) {
+		error = -EINVAL;
+		goto out_put_tmp_file;
+	}
+
 	ip = XFS_I(file_inode(f.file));
 	tip = XFS_I(file_inode(tmp.file));