diff options
| author | Rik van Riel <[email protected]> | 2017-07-12 14:36:33 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2017-07-12 16:26:03 -0700 |
| commit | c204d21f2232d875e36b8774c36ffd027dc1d606 (patch) | |
| tree | 5c2863061e09c1b22dcc956bb689ecd3a7bb0ea9 | |
| parent | 2c8340eda45cee1784f7b29e6d7dcc740ea3d02a (diff) | |
x86/mmap: properly account for stack randomization in mmap_base
When RLIMIT_STACK is, for example, 256MB, the current code results in a
gap between the top of the task and mmap_base of 256MB, failing to take
into account the amount by which the stack address was randomized. In
other words, the stack gets less than RLIMIT_STACK space.
Ensure that the gap between the stack and mmap_base always takes stack
randomization and the stack guard gap into account.
Obtained from Daniel Micay's linux-hardened tree.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Daniel Micay <[email protected]>
Signed-off-by: Rik van Riel <[email protected]>
Reported-by: Florian Weimer <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Daniel Micay <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Catalin Marinas <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | arch/x86/mm/mmap.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index 797295e792b2..229d04a83f85 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -92,13 +92,18 @@ unsigned long arch_mmap_rnd(void) static unsigned long mmap_base(unsigned long rnd, unsigned long task_size) { unsigned long gap = rlimit(RLIMIT_STACK); + unsigned long pad = stack_maxrandom_size(task_size) + stack_guard_gap; unsigned long gap_min, gap_max; + /* Values close to RLIM_INFINITY can overflow. */ + if (gap + pad > gap) + gap += pad; + /* * Top of mmap area (just below the process stack). * Leave an at least ~128 MB hole with possible stack randomization. */ - gap_min = SIZE_128M + stack_maxrandom_size(task_size); + gap_min = SIZE_128M; gap_max = (task_size / 6) * 5; if (gap < gap_min) |