Re: net/icmp: null-ptr-deref in ping_v4_push_pending_frames
From: Andrey Konovalov <hidden>
Date: 2017-02-07 14:43:35
Also in:
lkml
On Mon, Feb 6, 2017 at 11:50 PM, Cong Wang [off-list ref] wrote:
On Mon, Feb 6, 2017 at 11:39 AM, Andrey Konovalov [off-list ref] wrote:quoted
Hi, I've got the following error report while running the syzkaller fuzzer. The null-ptr-deref is caused by sendto() on a socket(PF_INET, SOCK_DGRAM, PROT_ICMP). Note, that this requires the ability to create such sockets, which can be configured by net.ipv4.ping_group_range (https://lwn.net/Articles/422330/). A reproducer and .config are attached. On commit a572a1b999489efb591287632279c6c9eca3e4ed. 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 RIP: 0033:0x445879 RSP: 002b:00007f6f7c715b58 EFLAGS: 00000282 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000445879 RDX: 0000000000000008 RSI: 0000000020001000 RDI: 0000000000000005 RBP: 00000000006e1ca0 R08: 0000000020ed9ff0 R09: 0000000000000010 R10: 0000000020000010 R11: 0000000000000282 R12: 0000000000708000 R13: 0000000000000000 R14: 00007f6f7c7169c0 R15: 00007f6f7c716700 Code: 38 ca 7c 08 84 c9 0f 85 35 03 00 00 49 8d bf c2 00 00 00 66 89 83 a2 fe ff ff 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85 RIP: ping_v4_push_pending_frames net/ipv4/ping.c:647 [inline] RSP: ffff880069bef8b8 RIP: ping_v4_sendmsg+0x1acd/0x23f0 net/ipv4/ping.c:837 RSP: ffff880069bef8b8 ---[ end trace 13dad24b243d08a7 ]---This fixes it for me:
Hi Cong, This fixes it for me as well. Will you mail the patch upstream? Thanks! Tested-by: Andrey Konovalov <redacted>
quoted hunk ↗ jump to hunk
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c index 86cca61..68d77b1 100644 --- a/net/ipv4/ping.c +++ b/net/ipv4/ping.c@@ -642,6 +642,8 @@ 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); -- You received this message because you are subscribed to the Google Groups "syzkaller" group. To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller+unsubscribe@googlegroups.com. For more options, visit https://groups.google.com/d/optout.