splice: missing user pointer access verification (CVE-2008-0009/10)

patch 8811930dc74a503415b35c4a79d14fb0b408a361 in mainline.

vmsplice_to_user() must always check the user pointer and length
with access_ok() before copying. Likewise, for the slow path of
copy_from_user_mmap_sem() we need to check that we may read from
the user region.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Wojciech Purczynski <cliph@research.coseinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/splice.c b/fs/splice.c
index 02c39ae719b69a365ba4392f2ebfed4ae6e59651..2aa8f5ab1c49d5ca42ae1ec2ae7b04d6f0b2d0e1 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1234,6 +1234,9 @@ static int copy_from_user_mmap_sem(void *dst, const void __user *src, size_t n)
 {
        int partial;
 
+       if (!access_ok(VERIFY_READ, src, n))
+               return -EFAULT;
+
        pagefault_disable();
        partial = __copy_from_user_inatomic(dst, src, n);
        pagefault_enable();
@@ -1442,6 +1445,11 @@ static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
                        break;
                }
 
+               if (unlikely(!access_ok(VERIFY_WRITE, base, len))) {
+                       error = -EFAULT;
+                       break;
+               }
+
                sd.len = 0;
                sd.total_len = len;
                sd.flags = flags;