From 712a30e63c8066ed84385b12edbfb804f49cbc44 Mon Sep 17 00:00:00 2001
From: Bastian Blank <bastian@waldi.eu.org>
Date: Sun, 10 Feb 2008 16:47:57 +0200
Subject: [PATCH] splice: fix user pointer access in get_iovec_page_array()

Commit 8811930dc74a503415b35c4a79d14fb0b408a361 ("splice: missing user
pointer access verification") added the proper access_ok() calls to
copy_from_user_mmap_sem() which ensures we can copy the struct iovecs
from userspace to the kernel.

But we also must check whether we can access the actual memory region
pointed to by the struct iovec to fix the access checks properly.

Signed-off-by: Bastian Blank <waldi@debian.org>
Acked-by: Oliver Pinter <oliver.pntr@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/splice.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/splice.c b/fs/splice.c
index 14e2262c0a0..9b559ee711a 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1234,7 +1234,7 @@ static int get_iovec_page_array(const struct iovec __user *iov,
 		if (unlikely(!len))
 			break;
 		error = -EFAULT;
-		if (unlikely(!base))
+		if (!access_ok(VERIFY_READ, base, len))
 			break;
 
 		/*