• WANG Cong's avatar
    ping: fix a null pointer dereference · 25c09419
    WANG Cong authored
    [ Upstream commit 73d2c667 ]
    
    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: c319b4d7 ("net: ipv4: add IPPROTO_ICMP socket kind")
    Reported-by: default avatarAndrey Konovalov <andreyknvl@google.com>
    Tested-by: default avatarAndrey Konovalov <andreyknvl@google.com>
    Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
    25c09419
ping.c 29.2 KB