tree 5b1d7a869db512f1297c82142adf006c3c6786c0
parent bd4f490a079730aadfaf9a728303ea0135c01945
author Andi Kleen <andi@firstfloor.org> 1262990572 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1263231245 -0800

kernel/signal.c: fix kernel information leak with print-fatal-signals=1

When print-fatal-signals is enabled it's possible to dump any memory
reachable by the kernel to the log by simply jumping to that address from
user space.

Or crash the system if there's some hardware with read side effects.

The fatal signals handler will dump 16 bytes at the execution address,
which is fully controlled by ring 3.

In addition when something jumps to a unmapped address there will be up to
16 additional useless page faults, which might be potentially slow (and at
least is not very efficient)

Fortunately this option is off by default and only there on i386.

But fix it by checking for kernel addresses and also stopping when there's
a page fault.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>