lkml.org 
[lkml]   [2007]   [May]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    SubjectRe: [PATCH 1/2] limit print_fatal_signal() rate
    Date
    Andrew Morton wrote:
    > Well OK. But vdso-print-fatal-signals.patch is designated not-for-mainline
    > anyway.
    >
    > I think the DoS which you identify has been available for a very long time
    > on ia64, x86_64 and perhaps others.
    >

    For the mainline a fix could be the following...

    ---

    Limit the rate of the kernel logging for the segfaults of user applications, to
    avoid potential message floods or denial-of-service attacks.

    Signed-off-by: Andrea Righi <a.righi@cineca.it>

    diff -urpN linux-2.6.22-rc2/arch/avr32/mm/fault.c linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/avr32/mm/fault.c
    --- linux-2.6.22-rc2/arch/avr32/mm/fault.c 2007-05-19 13:11:30.000000000 +0200
    +++ linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/avr32/mm/fault.c 2007-05-21 11:48:37.000000000 +0200
    @@ -158,7 +158,7 @@ bad_area:
    up_read(&mm->mmap_sem);

    if (user_mode(regs)) {
    - if (exception_trace)
    + if (exception_trace && printk_ratelimit())
    printk("%s%s[%d]: segfault at %08lx pc %08lx "
    "sp %08lx ecr %lu\n",
    is_init(tsk) ? KERN_EMERG : KERN_INFO,
    diff -urpN linux-2.6.22-rc2/arch/x86_64/mm/fault.c linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/x86_64/mm/fault.c
    --- linux-2.6.22-rc2/arch/x86_64/mm/fault.c 2007-05-21 11:42:07.000000000 +0200
    +++ linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/x86_64/mm/fault.c 2007-05-21 11:45:55.000000000 +0200
    @@ -489,7 +489,8 @@ bad_area_nosemaphore:
    (address >> 32))
    return;

    - if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
    + if (exception_trace && unhandled_signal(tsk, SIGSEGV) &&
    + printk_ratelimit()) {
    printk(
    "%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
    tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/
    \
     
     \ /
      Last update: 2007-05-21 12:47    [W:0.023 / U:64.192 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site