• Rabin Vincent's avatar
    tracing/syscalls: Ignore numbers outside NR_syscalls' range · 3ad3add7
    Rabin Vincent authored
    commit 086ba77a6db00ed858ff07451bedee197df868c9 upstream.
    
    ARM has some private syscalls (for example, set_tls(2)) which lie
    outside the range of NR_syscalls.  If any of these are called while
    syscall tracing is being performed, out-of-bounds array access will
    occur in the ftrace and perf sys_{enter,exit} handlers.
    
     # trace-cmd record -e raw_syscalls:* true && trace-cmd report
     ...
     true-653   [000]   384.675777: sys_enter:            NR 192 (0, 1000, 3, 4000022, ffffffff, 0)
     true-653   [000]   384.675812: sys_exit:             NR 192 = 1995915264
     true-653   [000]   384.675971: sys_enter:            NR 983045 (76f74480, 76f74000, 76f74b28, 76f74480, 76f76f74, 1)
     true-653   [000]   384.675988: sys_exit:             NR 983045 = 0
     ...
    
     # trace-cmd record -e syscalls:* true
     [   17.289329] Unable to handle kernel paging request at virtual address aaaaaace
     [   17.289590] pgd = 9e71c000
     [   17.289696] [aaaaaace] *pgd=00000000
     [   17.289985] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
     [   17.290169] Modules linked in:
     [   17.290391] CPU: 0 PID: 704 Comm: true Not tainted 3.18.0-rc2+ #21
     [   17.290585] task: 9f4dab00 ti: 9e710000 task.ti: 9e710000
     [   17.290747] PC is at ftrace_syscall_enter+0x48/0x1f8
     [   17.290866] LR is at syscall_trace_enter+0x124/0x184
    
    Fix this by ignoring out-of-NR_syscalls-bounds syscall numbers.
    
    Commit cd0980fc "tracing: Check invalid syscall nr while tracing syscalls"
    added the check for less than zero, but it should have also checked
    for greater than NR_syscalls.
    
    Link: http://lkml.kernel.org/p/1414620418-29472-1-git-send-email-rabin@rab.in
    
    Fixes: cd0980fc "tracing: Check invalid syscall nr while tracing syscalls"
    Signed-off-by: default avatarRabin Vincent <rabin@rab.in>
    Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    3ad3add7
trace_syscalls.c 18.6 KB