This is a note to let you know that I've just added the patch titled
tty: n_gsm: add sanity check for gsm->receive in gsm_receive_buf()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-n_gsm-add-sanity-check-for-gsm-receive-in-gsm_receive_buf.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From Ilia.Gavrilov@xxxxxxxxxxx Tue Dec 12 12:17:23 2023
From: Gavrilov Ilia <Ilia.Gavrilov@xxxxxxxxxxx>
Date: Tue, 12 Dec 2023 11:17:21 +0000
Subject: tty: n_gsm: add sanity check for gsm->receive in gsm_receive_buf()
To: "stable@xxxxxxxxxxxxxxx" <stable@xxxxxxxxxxxxxxx>, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Daniel Starke <daniel.starke@xxxxxxxxxxx>, Jiri Slaby <jirislaby@xxxxxxxxxx>, Russ Gorby <russ.gorby@xxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, "lvc-project@xxxxxxxxxxxxxxxx" <lvc-project@xxxxxxxxxxxxxxxx>, "syzbot+e3563f0c94e188366dbb@xxxxxxxxxxxxxxxxxxxxxxxxx" <syzbot+e3563f0c94e188366dbb@xxxxxxxxxxxxxxxxxxxxxxxxx>, Mazin Al Haddad <mazinalhaddad05@xxxxxxxxx>
Message-ID: <20231212111431.4064760-4-Ilia.Gavrilov@xxxxxxxxxxx>
From: Mazin Al Haddad <mazinalhaddad05@xxxxxxxxx>
commit f16c6d2e58a4c2b972efcf9eb12390ee0ba3befb upstream
A null pointer dereference can happen when attempting to access the
"gsm->receive()" function in gsmld_receive_buf(). Currently, the code
assumes that gsm->receive is only called after MUX activation.
Since the gsmld_receive_buf() function can be accessed without the need to
initialize the MUX, the gsm->receive() function will not be set and a
NULL pointer dereference will occur.
Fix this by avoiding the call to "gsm->receive()" in case the function is
not initialized by adding a sanity check.
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
Link: https://syzkaller.appspot.com/bug?id=bdf035c61447f8c6e0e6920315d577cb5cc35ac5
Fixes: 01aecd917114 ("tty: n_gsm: fix tty registration before control channel open")
Reported-and-tested-by: syzbot+e3563f0c94e188366dbb@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Mazin Al Haddad <mazinalhaddad05@xxxxxxxxx>
Link: https://lore.kernel.org/r/20220814015211.84180-1-mazinalhaddad05@xxxxxxxxx
Signed-off-by: Gavrilov Ilia <Ilia.Gavrilov@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_gsm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2588,7 +2588,8 @@ static void gsmld_receive_buf(struct tty
flags = *fp++;
switch (flags) {
case TTY_NORMAL:
- gsm->receive(gsm, *cp);
+ if (gsm->receive)
+ gsm->receive(gsm, *cp);
break;
case TTY_OVERRUN:
case TTY_BREAK:
Patches currently in stable-queue which might be from Ilia.Gavrilov@xxxxxxxxxxx are
queue-5.10/tty-n_gsm-add-sanity-check-for-gsm-receive-in-gsm_receive_buf.patch
queue-5.10/tty-n_gsm-fix-tty-registration-before-control-channel-open.patch
queue-5.10/tty-n_gsm-remove-duplicates-of-parameters.patch
