| From 532ce350200e702a4073c85e9a792ad82e1bce6e Mon Sep 17 00:00:00 2001 |
| From: WANG Cong <xiyou.wangcong@gmail.com> |
| Date: Tue, 7 Feb 2017 12:59:46 -0800 |
| Subject: [PATCH] ping: fix a null pointer dereference |
| |
| commit 73d2c6678e6c3af7e7a42b1e78cd0211782ade32 upstream. |
| |
| Andrey reported a kernel crash: |
| |
| general protection fault: 0000 [#1] SMP KASAN |
| Dumping ftrace buffer: |
| (ftrace buffer empty) |
| Modules linked in: |
| CPU: 2 PID: 3880 Comm: syz-executor1 Not tainted 4.10.0-rc6+ #124 |
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 |
| task: ffff880060048040 task.stack: ffff880069be8000 |
| RIP: 0010:ping_v4_push_pending_frames net/ipv4/ping.c:647 [inline] |
| RIP: 0010:ping_v4_sendmsg+0x1acd/0x23f0 net/ipv4/ping.c:837 |
| RSP: 0018:ffff880069bef8b8 EFLAGS: 00010206 |
| RAX: dffffc0000000000 RBX: ffff880069befb90 RCX: 0000000000000000 |
| RDX: 0000000000000018 RSI: ffff880069befa30 RDI: 00000000000000c2 |
| RBP: ffff880069befbb8 R08: 0000000000000008 R09: 0000000000000000 |
| R10: 0000000000000002 R11: 0000000000000000 R12: ffff880069befab0 |
| R13: ffff88006c624a80 R14: ffff880069befa70 R15: 0000000000000000 |
| FS: 00007f6f7c716700(0000) GS:ffff88006de00000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| CR2: 00000000004a6f28 CR3: 000000003a134000 CR4: 00000000000006e0 |
| Call Trace: |
| inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:744 |
| sock_sendmsg_nosec net/socket.c:635 [inline] |
| sock_sendmsg+0xca/0x110 net/socket.c:645 |
| SYSC_sendto+0x660/0x810 net/socket.c:1687 |
| SyS_sendto+0x40/0x50 net/socket.c:1655 |
| entry_SYSCALL_64_fastpath+0x1f/0xc2 |
| |
| This is because we miss a check for NULL pointer for skb_peek() when |
| the queue is empty. Other places already have the same check. |
| |
| Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind") |
| Reported-by: Andrey Konovalov <andreyknvl@google.com> |
| Tested-by: Andrey Konovalov <andreyknvl@google.com> |
| Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c |
| index dcdd5aed7eb1..50e1b7cd9c07 100644 |
| --- a/net/ipv4/ping.c |
| +++ b/net/ipv4/ping.c |
| @@ -647,6 +647,8 @@ static int ping_v4_push_pending_frames(struct sock *sk, struct pingfakehdr *pfh, |
| { |
| struct sk_buff *skb = skb_peek(&sk->sk_write_queue); |
| |
| + if (!skb) |
| + return 0; |
| pfh->wcheck = csum_partial((char *)&pfh->icmph, |
| sizeof(struct icmphdr), pfh->wcheck); |
| pfh->icmph.checksum = csum_fold(pfh->wcheck); |
| -- |
| 2.12.0 |
| |