From: linux@weissschuh.net
To: George Kennedy <george.kennedy@oracle.com>
Cc: jirislaby@kernel.org, gregkh@linuxfoundation.org,
torvalds@linux-foundation.org, sfr@canb.auug.org.au,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-serial@vger.kernel.org, regressions@lists.linux.dev
Subject: Re: [PATCH v2] vc_screen: modify vcs_size() handling in vcs_read()
Date: Tue, 28 Feb 2023 01:45:56 +0000 [thread overview]
Message-ID: <face2b1b-0f2e-4a79-a71b-79681fc56273@t-8ch.de> (raw)
In-Reply-To: <1677529301-19530-1-git-send-email-george.kennedy@oracle.com>
Hi,
On Mon, Feb 27, 2023 at 03:21:41PM -0500, George Kennedy wrote:
> Restore the vcs_size() handling in vcs_read() to what
> it had been in previous version.
This still seems to be broken for me.
Testcase:
# cat /dev/vcsa1
[.. data, looks complete ..]
cat: /dev/vcsa1: No such device or address
"ret" is still unconditionally overwritten with -ENXIO at the beginning
of the loop.
And when we break the loop because everything has been read in
`if (pos >= size)` then this error is returned to userspace instead of
just `0`.
I still need the patch from
https://lore.kernel.org/lkml/20230220064612.1783-1-linux@weissschuh.net/
> Fixes: 226fae124b2d ("vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF")
> Suggested-by: Jiri Slaby <jirislaby@kernel.org>
> Signed-off-by: George Kennedy <george.kennedy@oracle.com>
> ---
> v2: added Fixes
>
> drivers/tty/vt/vc_screen.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
> index f566eb1839dc..c0a2273bb998 100644
> --- a/drivers/tty/vt/vc_screen.c
> +++ b/drivers/tty/vt/vc_screen.c
> @@ -414,10 +414,8 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
> */
> size = vcs_size(vc, attr, uni_mode);
> if (size < 0) {
> - if (read)
> - break;
> ret = size;
> - goto unlock_out;
> + break;
> }
> if (pos >= size)
> break;
> --
> 2.31.1
>
next prev parent reply other threads:[~2023-02-28 1:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-27 20:21 [PATCH v2] vc_screen: modify vcs_size() handling in vcs_read() George Kennedy
2023-02-28 0:12 ` Linus Torvalds
2023-02-28 1:45 ` linux [this message]
2023-02-28 1:58 ` Linus Torvalds
2023-02-28 2:18 ` Thomas Weißschuh
2023-02-28 2:40 ` Linus Torvalds
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