linux/arch/parisc
Helge Deller d045c77c1a parisc,metag: Fix crashes due to stack randomization on stack-grows-upwards architectures
On architectures where the stack grows upwards (CONFIG_STACK_GROWSUP=y,
currently parisc and metag only) stack randomization sometimes leads to crashes
when the stack ulimit is set to lower values than STACK_RND_MASK (which is 8 MB
by default if not defined in arch-specific headers).

The problem is, that when the stack vm_area_struct is set up in fs/exec.c, the
additional space needed for the stack randomization (as defined by the value of
STACK_RND_MASK) was not taken into account yet and as such, when the stack
randomization code added a random offset to the stack start, the stack
effectively got smaller than what the user defined via rlimit_max(RLIMIT_STACK)
which then sometimes leads to out-of-stack situations and crashes.

This patch fixes it by adding the maximum possible amount of memory (based on
STACK_RND_MASK) which theoretically could be added by the stack randomization
code to the initial stack size. That way, the user-defined stack size is always
guaranteed to be at minimum what is defined via rlimit_max(RLIMIT_STACK).

This bug is currently not visible on the metag architecture, because on metag
STACK_RND_MASK is defined to 0 which effectively disables stack randomization.

The changes to fs/exec.c are inside an "#ifdef CONFIG_STACK_GROWSUP"
section, so it does not affect other platformws beside those where the
stack grows upwards (parisc and metag).

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: linux-parisc@vger.kernel.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Cc: stable@vger.kernel.org # v3.16+
2015-05-12 22:03:44 +02:00
..
configs parisc: Update defconfigs which were missing CONFIG_NET. 2014-09-24 14:34:29 -04:00
include parisc,metag: Fix crashes due to stack randomization on stack-grows-upwards architectures 2015-05-12 22:03:44 +02:00
kernel parisc,metag: Fix crashes due to stack randomization on stack-grows-upwards architectures 2015-05-12 22:03:44 +02:00
lib parisc: percpu: update comments referring to __get_cpu_var 2014-12-13 12:42:53 -08:00
math-emu
mm parisc: expose number of page table levels on Kconfig level 2015-04-14 16:49:02 -07:00
oprofile
defpalo.conf
install.sh
Kconfig parisc: expose number of page table levels on Kconfig level 2015-04-14 16:49:02 -07:00
Kconfig.debug
Makefile Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2015-02-19 10:07:08 -08:00
nm