[PATCH] compat_readv: Remove bogus area verify

From: Corey Minyard
Date: Fri Dec 27 2013 - 20:23:50 EST

The compat_do_readv_writev() function was doing a verify_area on the
incoming iov, but the nr_segs value is not checked. If someone passes
in a -1 for nr_segs, for instance, the function should return an EINVAL.
However, it returns a EFAULT because the verify_area fails because it
is checking an array of size MAX_UINT. The check is bogus, anyway,
because the next check, compat_rw_copy_check_uvector(), will do all
the necessary checking, anyway. The non-compat do_readv_writev()
function doesn't do this check, so I think it's safe to just remove
the code.

Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx>
fs/read_write.c | 4 ----
1 file changed, 4 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 58e440d..1193ffd 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -901,10 +901,6 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
io_fn_t fn;
iov_fn_t fnv;

- ret = -EFAULT;
- if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector)))
- goto out;
ret = compat_rw_copy_check_uvector(type, uvector, nr_segs,
UIO_FASTIOV, iovstack, &iov);
if (ret <= 0)

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