• Davide Caratti's avatar
    net/smc: fix NULL pointer dereference on sock_create_kern() error path · a5dcb73b
    Davide Caratti authored
    when sock_create_kern(..., a) returns an error, 'a' might not be a valid
    pointer, so it shouldn't be dereferenced to read a->sk->sk_sndbuf and
    and a->sk->sk_rcvbuf; not doing that caused the following crash:
    
    general protection fault: 0000 [#1] SMP KASAN
    Dumping ftrace buffer:
        (ftrace buffer empty)
    Modules linked in:
    CPU: 0 PID: 4254 Comm: syzkaller919713 Not tainted 4.16.0-rc1+ #18
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
    Google 01/01/2011
    RIP: 0010:smc_create+0x14e/0x300 net/smc/af_smc.c:1410
    RSP: 0018:ffff8801b06afbc8 EFLAGS: 00010202
    RAX: dffffc0000000000 RBX: ffff8801b63457c0 RCX: ffffffff85a3e746
    RDX: 0000000000000004 RSI: 00000000ffffffff RDI: 0000000000000020
    RBP: ffff8801b06afbf0 R08: 00000000000007c0 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
    R13: ffff8801b6345c08 R14: 00000000ffffffe9 R15: ffffffff8695ced0
    FS:  0000000001afb880(0000) GS:ffff8801db200000(0000)
    knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000020000040 CR3: 00000001b0721004 CR4: 00000000001606f0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
      __sock_create+0x4d4/0x850 net/socket.c:1285
      sock_create net/socket.c:1325 [inline]
      SYSC_socketpair net/socket.c:1409 [inline]
      SyS_socketpair+0x1c0/0x6f0 net/socket.c:1366
      do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
      entry_SYSCALL_64_after_hwframe+0x26/0x9b
    RIP: 0033:0x4404b9
    RSP: 002b:00007fff44ab6908 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
    RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004404b9
    RDX: 0000000000000000 RSI: 0000000000000001 RDI: 000000000000002b
    RBP: 00007fff44ab6910 R08: 0000000000000002 R09: 00007fff44003031
    R10: 0000000020000040 R11: 0000000000000246 R12: ffffffffffffffff
    R13: 0000000000000006 R14: 0000000000000000 R15: 0000000000000000
    Code: 48 c1 ea 03 80 3c 02 00 0f 85 b3 01 00 00 4c 8b a3 48 04 00 00 48
    b8
    00 00 00 00 00 fc ff df 49 8d 7c 24 20 48 89 fa 48 c1 ea 03 <80> 3c 02
    00
    0f 85 82 01 00 00 4d 8b 7c 24 20 48 b8 00 00 00 00
    RIP: smc_create+0x14e/0x300 net/smc/af_smc.c:1410 RSP: ffff8801b06afbc8
    
    Fixes: cd6851f3 smc: remote memory buffers (RMBs)
    Reported-and-tested-by: syzbot+aa0227369be2dcc26ebe@syzkaller.appspotmail.com
    Signed-off-by: default avatarDavide Caratti <dcaratti@redhat.com>
    Signed-off-by: default avatarUrsula Braun <ubraun@linux.vnet.ibm.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    a5dcb73b
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