lkml.org 
[lkml]   [2019]   [Nov]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: Bug report - slab-out-of-bounds in vcs_scr_readw
On Mon, 4 Nov 2019, Or Cohen wrote:

> @gregkh@linuxfoundation.org @nico@fluxnic.net - Thanks for the quick response.
> @gregkh@linuxfoundation.org - Regarding your question, I don't think
> the 1 byte buffer is related to the problem. ( it's just was there in
> the initial reproducer the fuzzer created, and I forgot to remove it
> while reducing code from the reproducer ).

I think I know what the problem is. I have no time to test it though.

Please try this (untested) patch. Also please try running the same test
code but with vcsa6 in addition to vcsu6 to be sure.

---------- >8
Subject: [PATCH] vcs: add missing validation on vcs_size() returned value

One usage instance didn't account for the fact that vcs_size() may
return a negative error code.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>

diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index 1f042346e7..fa07d79027 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -474,6 +474,10 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
goto unlock_out;

size = vcs_size(inode);
+ if (size < 0) {
+ ret = size;
+ goto unlock_out;
+ }
ret = -EINVAL;
if (pos < 0 || pos > size)
goto unlock_out;
\
 
 \ /
  Last update: 2019-11-04 19:35    [W:0.068 / U:0.112 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site