Re: KASAN: slab-out-of-bounds Read in vcs_scr_readw

[Nicolas Pitre]

On Tue, 3 Dec 2019, syzbot wrote:

> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    596cf45c Merge branch 'akpm' (patches from Andrew)
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14c1d196e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8eb54eee6e6ca4a7
> dashboard link: https://syzkaller.appspot.com/bug?extid=7d027845265d531ba506
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11c6090ee00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13821b7ae00000
> 
> The bug was bisected to:
> 
> commit d21b0be246bf3bbf569e6e239f56abb529c7154e
> Author: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>
> Date:   Wed Jun 27 03:56:41 2018 +0000
> 
>    vt: introduce unicode mode for /dev/vcs
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1292fbf2e00000
> final crash:    https://syzkaller.appspot.com/x/report.txt?x=1192fbf2e00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=1692fbf2e00000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+7d027845265d531ba506@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: d21b0be246bf ("vt: introduce unicode mode for /dev/vcs")

This is most likely the same issue that was fixed and queued for 
mainline already. The fix is accessible as commit 0c9acb1af77a in the 
linux-next tree.


Nicolas