All of lore.kernel.org
 help / color / mirror / Atom feed
From: Greg KH <gregkh@linuxfoundation.org>
To: Mazin Al Haddad <mazinalhaddad05@gmail.com>
Cc: jirislaby@kernel.org, daniel.starke@siemens.com,
	linux-kernel@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org,
	skhan@linuxfoundation.org, paskripkin@gmail.com,
	syzbot+e3563f0c94e188366dbb@syzkaller.appspotmail.com
Subject: Re: [PATCH] tty: n_gsm: fix missing assignment of gsm->receive() in gsmld_attach_gsm()
Date: Wed, 10 Aug 2022 07:18:24 +0200	[thread overview]
Message-ID: <YvM/oKdt/NPfOiXS@kroah.com> (raw)
In-Reply-To: <20220810031251.91291-1-mazinalhaddad05@gmail.com>

On Wed, Aug 10, 2022 at 06:12:52AM +0300, Mazin Al Haddad wrote:
> Fixes a bug reported by syzbot.

I do not understand this sentence :(

> A null pointer dereference can
> happen when attempting to access the "gsm->receive()" function in
> gsmld_receive_buf(). Currently, the "gsm->receive()" function is only set
> after a call to the GSMIO_SETCONF ioctl. Since the gsmld_receive_buf()
> function can be accessed without the need to call the line discipline
> ioctl (GSMIO_SETCONF), the gsm->receive() function will not be set and a
> NULL pointer dereference will occur.
> 
> Fix this by setting the gsm->receive() function when the line discipline
> is being attached to the terminal device, inside gsmld_attach_gsm(). This
> will guarantee that the function is assigned and a call to TIOCSTI,
> which calls gsmld_receive_buf(), will not reference a null pointer.
> 
> Call Trace:
>  <TASK>
>  gsmld_receive_buf+0x1c2/0x2f0 drivers/tty/n_gsm.c:2861
>  tiocsti drivers/tty/tty_io.c:2293 [inline]
>  tty_ioctl+0xa75/0x15d0 drivers/tty/tty_io.c:2692
>  vfs_ioctl fs/ioctl.c:51 [inline]
>  __do_sys_ioctl fs/ioctl.c:870 [inline]
>  __se_sys_ioctl fs/ioctl.c:856 [inline]
>  __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> 
> 
> Fixes: 01aecd917114 ("tty: n_gsm: fix tty registration before control channel open")
> Reported-and-tested-by: syzbot+e3563f0c94e188366dbb@syzkaller.appspotmail.com
> Signed-off-by: Mazin Al Haddad <mazinalhaddad05@gmail.com>

What commit does this fix?

thanks,

greg k-h

WARNING: multiple messages have this Message-ID (diff)
From: Greg KH <gregkh@linuxfoundation.org>
To: Mazin Al Haddad <mazinalhaddad05@gmail.com>
Cc: daniel.starke@siemens.com, jirislaby@kernel.org,
	paskripkin@gmail.com,
	syzbot+e3563f0c94e188366dbb@syzkaller.appspotmail.com,
	linux-kernel@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [PATCH] tty: n_gsm: fix missing assignment of gsm->receive() in gsmld_attach_gsm()
Date: Wed, 10 Aug 2022 07:18:24 +0200	[thread overview]
Message-ID: <YvM/oKdt/NPfOiXS@kroah.com> (raw)
In-Reply-To: <20220810031251.91291-1-mazinalhaddad05@gmail.com>

On Wed, Aug 10, 2022 at 06:12:52AM +0300, Mazin Al Haddad wrote:
> Fixes a bug reported by syzbot.

I do not understand this sentence :(

> A null pointer dereference can
> happen when attempting to access the "gsm->receive()" function in
> gsmld_receive_buf(). Currently, the "gsm->receive()" function is only set
> after a call to the GSMIO_SETCONF ioctl. Since the gsmld_receive_buf()
> function can be accessed without the need to call the line discipline
> ioctl (GSMIO_SETCONF), the gsm->receive() function will not be set and a
> NULL pointer dereference will occur.
> 
> Fix this by setting the gsm->receive() function when the line discipline
> is being attached to the terminal device, inside gsmld_attach_gsm(). This
> will guarantee that the function is assigned and a call to TIOCSTI,
> which calls gsmld_receive_buf(), will not reference a null pointer.
> 
> Call Trace:
>  <TASK>
>  gsmld_receive_buf+0x1c2/0x2f0 drivers/tty/n_gsm.c:2861
>  tiocsti drivers/tty/tty_io.c:2293 [inline]
>  tty_ioctl+0xa75/0x15d0 drivers/tty/tty_io.c:2692
>  vfs_ioctl fs/ioctl.c:51 [inline]
>  __do_sys_ioctl fs/ioctl.c:870 [inline]
>  __se_sys_ioctl fs/ioctl.c:856 [inline]
>  __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> 
> 
> Fixes: 01aecd917114 ("tty: n_gsm: fix tty registration before control channel open")
> Reported-and-tested-by: syzbot+e3563f0c94e188366dbb@syzkaller.appspotmail.com
> Signed-off-by: Mazin Al Haddad <mazinalhaddad05@gmail.com>

What commit does this fix?

thanks,

greg k-h
_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

  reply	other threads:[~2022-08-10  8:50 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-10  3:12 [PATCH] tty: n_gsm: fix missing assignment of gsm->receive() in gsmld_attach_gsm() Mazin Al Haddad
2022-08-10  3:12 ` Mazin Al Haddad
2022-08-10  5:18 ` Greg KH [this message]
2022-08-10  5:18   ` Greg KH
2022-08-10  9:08 Starke, Daniel
2022-08-10  9:08 ` Starke, Daniel
2022-08-12 19:41 ` Mazin Al Haddad
2022-08-12 19:41   ` Mazin Al Haddad

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YvM/oKdt/NPfOiXS@kroah.com \
    --to=gregkh@linuxfoundation.org \
    --cc=daniel.starke@siemens.com \
    --cc=jirislaby@kernel.org \
    --cc=linux-kernel-mentees@lists.linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mazinalhaddad05@gmail.com \
    --cc=paskripkin@gmail.com \
    --cc=skhan@linuxfoundation.org \
    --cc=syzbot+e3563f0c94e188366dbb@syzkaller.appspotmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.