Commit af0f4297 authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Linus Torvalds

arm: properly account for stack randomization and stack guard gap

This commit takes care of stack randomization and stack guard gap when
computing mmap base address and checks if the task asked for
randomization.  This fixes the problem uncovered and not fixed for arm
here: https://lkml.kernel.org/r/20170622200033.25714-1-riel@redhat.com

Link: http://lkml.kernel.org/r/20190730055113.23635-7-alex@ghiti.frSigned-off-by: default avatarAlexandre Ghiti <alex@ghiti.fr>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: James Hogan <jhogan@kernel.org>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e7142bf5
...@@ -18,8 +18,9 @@ ...@@ -18,8 +18,9 @@
(((pgoff)<<PAGE_SHIFT) & (SHMLBA-1))) (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
/* gap between mmap and stack */ /* gap between mmap and stack */
#define MIN_GAP (128*1024*1024UL) #define MIN_GAP (128*1024*1024UL)
#define MAX_GAP ((TASK_SIZE)/6*5) #define MAX_GAP ((TASK_SIZE)/6*5)
#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
static int mmap_is_legacy(struct rlimit *rlim_stack) static int mmap_is_legacy(struct rlimit *rlim_stack)
{ {
...@@ -35,6 +36,15 @@ static int mmap_is_legacy(struct rlimit *rlim_stack) ...@@ -35,6 +36,15 @@ static int mmap_is_legacy(struct rlimit *rlim_stack)
static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
{ {
unsigned long gap = rlim_stack->rlim_cur; unsigned long gap = rlim_stack->rlim_cur;
unsigned long pad = stack_guard_gap;
/* Account for stack randomization if necessary */
if (current->flags & PF_RANDOMIZE)
pad += (STACK_RND_MASK << PAGE_SHIFT);
/* Values close to RLIM_INFINITY can overflow. */
if (gap + pad > gap)
gap += pad;
if (gap < MIN_GAP) if (gap < MIN_GAP)
gap = MIN_GAP; gap = MIN_GAP;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment