mm: fix overflow check in expand_upwards()
authorHelge Deller <deller@gmx.de>
Fri, 14 Jul 2017 21:49:38 +0000 (14:49 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 14 Jul 2017 22:05:12 +0000 (15:05 -0700)
commit37511fb5c91db93d8bd6e3f52f86e5a7ff7cfcdf
tree2c90b067bcd763a46b9712118bbba0c53285c247
parentb86faee6d111294fa95a2e89b5f771b2da3c9782
mm: fix overflow check in expand_upwards()

Jörn Engel noticed that the expand_upwards() function might not return
-ENOMEM in case the requested address is (unsigned long)-PAGE_SIZE and
if the architecture didn't defined TASK_SIZE as multiple of PAGE_SIZE.

Affected architectures are arm, frv, m68k, blackfin, h8300 and xtensa
which all define TASK_SIZE as 0xffffffff, but since none of those have
an upwards-growing stack we currently have no actual issue.

Nevertheless let's fix this just in case any of the architectures with
an upward-growing stack (currently parisc, metag and partly ia64) define
TASK_SIZE similar.

Link: http://lkml.kernel.org/r/20170702192452.GA11868@p100.box
Fixes: bd726c90b6b8 ("Allow stack to grow up to address space limit")
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: Jörn Engel <joern@purestorage.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/mmap.c