[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAHpGcMK0C6uxuNwhOouHLz7fyCcu=JH63COX_0J72koZk_CS7w@mail.gmail.com>
Date: Mon, 24 Oct 2022 11:42:49 +0200
From: Andreas Grünbacher <andreas.gruenbacher@...il.com>
To: Hawkins Jiawei <yin31149@...il.com>
Cc: Bob Peterson <rpeterso@...hat.com>,
Andreas Gruenbacher <agruenba@...hat.com>, 18801353760@....com,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
syzbot+da97a57c5b742d05db51@...kaller.appspotmail.com,
cluster-devel@...hat.com, syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH -next 4/5] gfs2: fix possible null-ptr-deref when parsing param
Am So., 23. Okt. 2022 um 18:46 Uhr schrieb Hawkins Jiawei <yin31149@...il.com>:
> According to commit "vfs: parse: deal with zero length string value",
> kernel will set the param->string to null pointer in vfs_parse_fs_string()
> if fs string has zero length.
>
> Yet the problem is that, gfs2_parse_param() will dereferences the
> param->string, without checking whether it is a null pointer, which may
> trigger a null-ptr-deref bug.
>
> This patch solves it by adding sanity check on param->string
> in gfs2_parse_param().
Yes, but then it dereferences param->string in the error message. That
won't help.
> Reported-by: syzbot+da97a57c5b742d05db51@...kaller.appspotmail.com
> Tested-by: syzbot+da97a57c5b742d05db51@...kaller.appspotmail.com
> Cc: agruenba@...hat.com
> Cc: cluster-devel@...hat.com
> Cc: linux-kernel@...r.kernel.org
> Cc: rpeterso@...hat.com
> Cc: syzkaller-bugs@...glegroups.com
> Signed-off-by: Hawkins Jiawei <yin31149@...il.com>
> ---
> fs/gfs2/ops_fstype.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
> index c0cf1d2d0ef5..934746f18c25 100644
> --- a/fs/gfs2/ops_fstype.c
> +++ b/fs/gfs2/ops_fstype.c
> @@ -1446,12 +1446,18 @@ static int gfs2_parse_param(struct fs_context *fc, struct fs_parameter *param)
>
> switch (o) {
> case Opt_lockproto:
> + if (!param->string)
> + goto bad_val;
> strscpy(args->ar_lockproto, param->string, GFS2_LOCKNAME_LEN);
> break;
> case Opt_locktable:
> + if (!param->string)
> + goto bad_val;
> strscpy(args->ar_locktable, param->string, GFS2_LOCKNAME_LEN);
> break;
> case Opt_hostdata:
> + if (!param->string)
> + goto bad_val;
> strscpy(args->ar_hostdata, param->string, GFS2_LOCKNAME_LEN);
> break;
> case Opt_spectator:
> @@ -1535,6 +1541,10 @@ static int gfs2_parse_param(struct fs_context *fc, struct fs_parameter *param)
> return invalfc(fc, "invalid mount option: %s", param->key);
> }
> return 0;
> +
> +bad_val:
> + return invalfc(fc, "Bad value '%s' for mount option '%s'\n",
> + param->string, param->key);
> }
>
> static int gfs2_reconfigure(struct fs_context *fc)
> --
> 2.25.1
>
Thanks,
Andreas
Powered by blists - more mailing lists