From: Zhang Qilong Date: Fri, 28 Oct 2022 16:10:49 +0000 (+0800) Subject: rose: Fix NULL pointer dereference in rose_send_frame() X-Git-Tag: v5.15.79~236 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3e2129c67daca21043a26575108f6286c85e71f6;p=platform%2Fkernel%2Flinux-rpi.git 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: 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 [...] 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 Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- diff --git a/net/rose/rose_link.c b/net/rose/rose_link.c index f6102e6..730d220 100644 --- a/net/rose/rose_link.c +++ b/net/rose/rose_link.c @@ -236,6 +236,9 @@ 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)