This is a note to let you know that I've just added the patch titled
rose: Fix NULL pointer dereference in rose_send_frame()
to the 4.9-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:
rose-fix-null-pointer-dereference-in-rose_send_frame.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 84768ed58a12698094813a6220562ea60cfcec3c
Author: Zhang Qilong <zhangqilong3@xxxxxxxxxx>
Date: Sat Oct 29 00:10:49 2022 +0800
rose: Fix NULL pointer dereference in rose_send_frame()
[ Upstream commit e97c089d7a49f67027395ddf70bf327eeac2611e ]
The syzkaller reported an issue:
KASAN: null-ptr-deref in range [0x0000000000000380-0x0000000000000387]
CPU: 0 PID: 4069 Comm: kworker/0:15 Not tainted 6.0.0-syzkaller-02734-g0326074ff465 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
Workqueue: rcu_gp srcu_invoke_callbacks
RIP: 0010:rose_send_frame+0x1dd/0x2f0 net/rose/rose_link.c:101
Call Trace:
<IRQ>
rose_transmit_clear_request+0x1d5/0x290 net/rose/rose_link.c:255
rose_rx_call_request+0x4c0/0x1bc0 net/rose/af_rose.c:1009
rose_loopback_timer+0x19e/0x590 net/rose/rose_loopback.c:111
call_timer_fn+0x1a0/0x6b0 kernel/time/timer.c:1474
expire_timers kernel/time/timer.c:1519 [inline]
__run_timers.part.0+0x674/0xa80 kernel/time/timer.c:1790
__run_timers kernel/time/timer.c:1768 [inline]
run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1803
__do_softirq+0x1d0/0x9c8 kernel/softirq.c:571
[...]
</IRQ>
It triggers NULL pointer dereference when 'neigh->dev->dev_addr' is
called in the rose_send_frame(). It's the first occurrence of the
`neigh` is in rose_loopback_timer() as `rose_loopback_neigh', and
the 'dev' in 'rose_loopback_neigh' is initialized sa nullptr.
It had been fixed by commit 3b3fd068c56e3fbea30090859216a368398e39bf
("rose: Fix Null pointer dereference in rose_send_frame()") ever.
But it's introduced by commit 3c53cd65dece47dd1f9d3a809f32e59d1d87b2b8
("rose: check NULL rose_loopback_neigh->loopback") again.
We fix it by add NULL check in rose_transmit_clear_request(). When
the 'dev' in 'neigh' is NULL, we don't reply the request and just
clear it.
syzkaller don't provide repro, and I provide a syz repro like:
r0 = syz_init_net_socket$bt_sco(0x1f, 0x5, 0x2)
ioctl$sock_inet_SIOCSIFFLAGS(r0, 0x8914, &(0x7f0000000180)={'rose0\x00', 0x201})
r1 = syz_init_net_socket$rose(0xb, 0x5, 0x0)
bind$rose(r1, &(0x7f00000000c0)=@full={0xb, @dev, @null, 0x0, [@null, @null, @netrom, @netrom, @default, @null]}, 0x40)
connect$rose(r1, &(0x7f0000000240)=@short={0xb, @dev={0xbb, 0xbb, 0xbb, 0x1, 0x0}, @remote={0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0x1}, 0x1, @netrom={0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0x0, 0x0}}, 0x1c)
Fixes: 3c53cd65dece ("rose: check NULL rose_loopback_neigh->loopback")
Signed-off-by: Zhang Qilong <zhangqilong3@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/rose/rose_link.c b/net/rose/rose_link.c
index c76638cc2cd5..4e02634e4a66 100644
--- a/net/rose/rose_link.c
+++ b/net/rose/rose_link.c
@@ -241,6 +241,9 @@ void rose_transmit_clear_request(struct rose_neigh *neigh, unsigned int lci, uns
unsigned char *dptr;
int len;
+ if (!neigh->dev)
+ return;
+
len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + ROSE_MIN_LEN + 3;
if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
