[lkml]   [2007]   [Sep]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectLinux 2.4.36-pre1

    I've just released Linux 2.4.36-pre1.

    It's basically the same as, with an add-on I'd like people
    to experiment with : In private discussions, Solar Designer proposed
    to restrict the ability to map the NULL address to CAP_RAW_IO capable
    processes only. The idea behind this was to prevent "normal" users
    from trying to exploit NULL dereferences in the kernel which have
    not been discovered yet. This is purely a preventive measure. Alan
    Cox indicated that it was desirable to be able to dynamically disable
    the feature because some (very) rare programs map the NULL pointer
    to speed up their walk through linked lists by avoiding NULL pointer

    Chris Wright noted that 2.6 already has a somewhat similar feature
    brought by Eric Paris, which introduces a sysctl by which the admin
    can set the lower mappable address.

    Finally a combination of both methods was implemented. The same sysctl
    as in 2.6 was implemented to set the lowest mappable address for non
    CAP_RAW_IO capable processes. By default, it is set to zero (disabled)
    which means NULL is mappable for everybody. To enable protection,
    simply echo the first mappable address into /proc/sys/vm/mmap_min_addr :

    # echo 4096 > /proc/sys/vm/mmap_min_addr

    We chose to use the same sysctl and semantics as in 2.6 to ease the
    transition from 2.4 to 2.6 without requiring to remove protection.

    Extensive tests have been ran with this feature. Some of my desktop
    machines already run with it enabled, and our appliances at Exceliance
    ship with it enabled by default. Solar Designer tested both Xorg and
    Wine as a normal user, and the same feature is enabled by default in
    the Openwall Linux 2.4.35-ow2 kernel.

    Please report any breakage you would detect when enabling it. We're
    pretty confident that almost every applications will not see any
    difference since no normal application maps NULL. But it would be
    interesting to identify the "special" ones. Applications running
    as root will never be impacted. Depending on the application,
    typical breakage would translate into memory allocation error or
    segmentation fault. Something clearly detectable anyway.

    Another issue I'll try to get solved is the current status of the
    e100 driver. I got hit in production by its very unreliable VLAN
    support (version 2.3.43 !). I got 3.5.17 to fix all of my issues,
    so I'll check with the e100 maintainers if we can upgrade it. It
    will make the maintenance easier for them too by getting rid of
    a very old and buggy version.

    Last but not least, please note that this version _will not_ build
    under gcc-4.2, so it's not necessary to report it. I'll try to find
    a solution.

    I estimate that depending on what will be updated, 2.4.36 could see
    the light by the end of this year. 2.4.35.x will still evolve in
    parallel, of course !


    The patch and changelog will appear soon at the following locations:

    Git repository:

    Git repository through the gitweb interface:

    Summary of changes from v2.4.35 to v2.4.36-pre1

    Marc Haisenko (1):
    b44: fix force mac address before ifconfig up

    Willy Tarreau (12):
    build fix for lvm with gcc 4
    fix wdt83627 build breakage with gcc 4.x
    wdt83627: fix wdt_init() return code
    module fdomain_cs requires fdomain_setup()
    do not use gcc's builtin strpbrk
    fix incorrect use of -fno-unit-at-a-time on GCC >= 4
    second build fix for some rare buggy versions of GCC 4
    CVE-2007-3848 Privilege escalation via PR_SET_PDEATHSIG
    i386: do_test_wp_bit() must not be inlined
    restore -fno-unit-at-a-time on GCC >= 4
    sysctl to prevent normal processes from mapping NULL
    Change VERSION to 2.4.36-pre1

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2007-09-08 20:49    [W:0.023 / U:13.432 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site