• Linus Torvalds's avatar
    Revert "kernel: make /proc/kallsyms mode 400 to reduce ease of attacking" · 33e0d57f
    Linus Torvalds authored
    This reverts commit 59365d13.
    It turns out that this can break certain existing user land setups.
    Quoth Sarah Sharp:
     "On Wednesday, I updated my branch to commit 460781b5 from linus' tree,
      and my box would not boot.  klogd segfaulted, which stalled the whole
      At first I thought it actually hung the box, but it continued booting
      after 5 minutes, and I was able to log in.  It dropped back to the
      text console instead of the graphical bootup display for that period
      of time.  dmesg surprisingly still works.  I've bisected the problem
      down to this commit (commit 59365d13)
      The box is running klogd 1.5.5ubuntu3 (from Jaunty).  Yes, I know
      that's old.  I read the bit in the commit about changing the
      permissions of kallsyms after boot, but if I can't boot that doesn't
    So let's just keep the old default, and encourage distributions to do
    the "chmod -r /proc/kallsyms" in their bootup scripts.  This is not
    worth a kernel option to change default behavior, since it's so easily
    done in user space.
    Reported-and-bisected-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
    Cc: Marcus Meissner <meissner@suse.de>
    Cc: Tejun Heo <tj@kernel.org>
    Cc: Eugene Teo <eugeneteo@kernel.org>
    Cc: Jesper Juhl <jj@chaosbits.net>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
kallsyms.c 12.9 KB