• Vlad Yasevich's avatar
    sctp: Fix a race between ICMP protocol unreachable and connect() · 50b5d6ad
    Vlad Yasevich authored
    ICMP protocol unreachable handling completely disregarded
    the fact that the user may have locked the socket.  It proceeded
    to destroy the association, even though the user may have
    held the lock and had a ref on the association.  This resulted
    in the following:
    Attempt to release alive inet socket f6afcc00
    [ BUG: held lock freed! ]
    somenu/2672 is freeing memory f6afcc00-f6afcfff, with a lock still held
     (sk_lock-AF_INET){+.+.+.}, at: [<c122098a>] sctp_connect+0x13/0x4c
    1 lock held by somenu/2672:
     #0:  (sk_lock-AF_INET){+.+.+.}, at: [<c122098a>] sctp_connect+0x13/0x4c
    stack backtrace:
    Pid: 2672, comm: somenu Not tainted 2.6.32-telco #55
    Call Trace:
     [<c1232266>] ? printk+0xf/0x11
     [<c1038553>] debug_check_no_locks_freed+0xce/0xff
     [<c10620b4>] kmem_cache_free+0x21/0x66
     [<c1185f25>] __sk_free+0x9d/0xab
     [<c1185f9c>] sk_free+0x1c/0x1e
     [<c1216e38>] sctp_association_put+0x32/0x89
     [<c1220865>] __sctp_connect+0x36d/0x3f4
     [<c122098a>] ? sctp_connect+0x13/0x4c
     [<c102d073>] ? autoremove_wake_function+0x0/0x33
     [<c12209a8>] sctp_connect+0x31/0x4c
     [<c11d1e80>] inet_dgram_connect+0x4b/0x55
     [<c11834fa>] sys_connect+0x54/0x71
     [<c103a3a2>] ? lock_release_non_nested+0x88/0x239
     [<c1054026>] ? might_fault+0x42/0x7c
     [<c1054026>] ? might_fault+0x42/0x7c
     [<c11847ab>] sys_socketcall+0x6d/0x178
     [<c10da994>] ? trace_hardirqs_on_thunk+0xc/0x10
     [<c1002959>] syscall_call+0x7/0xb
    This was because the sctp_wait_for_connect() would aqcure the socket
    lock and then proceed to release the last reference count on the
    association, thus cause the fully destruction path to finish freeing
    the socket.
    The simplest solution is to start a very short timer in case the socket
    is owned by user.  When the timer expires, we can do some verification
    and be able to do the release properly.
    Signed-off-by: default avatarVlad Yasevich <vladislav.yasevich@hp.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>