The patch titled Subject: arm: properly account for stack randomization and stack guard gap has been added to the -mm tree. Its filename is arm-properly-account-for-stack-randomization-and-stack-guard-gap.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/arm-properly-account-for-stack-randomization-and-stack-guard-gap.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/arm-properly-account-for-stack-randomization-and-stack-guard-gap.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Alexandre Ghiti <alex@xxxxxxxx> Subject: 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@xxxxxxxxxx Link: http://lkml.kernel.org/r/20190730055113.23635-7-alex@xxxxxxxx Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> Reviewed-by: Luis Chamberlain <mcgrof@xxxxxxxxxx> Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: James Hogan <jhogan@xxxxxxxxxx> Cc: Palmer Dabbelt <palmer@xxxxxxxxxx> Cc: Paul Burton <paul.burton@xxxxxxxx> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Cc: Russell King <linux@xxxxxxxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arm/mm/mmap.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) --- a/arch/arm/mm/mmap.c~arm-properly-account-for-stack-randomization-and-stack-guard-gap +++ a/arch/arm/mm/mmap.c @@ -18,8 +18,9 @@ (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1))) /* gap between mmap and stack */ -#define MIN_GAP (128*1024*1024UL) -#define MAX_GAP ((TASK_SIZE)/6*5) +#define MIN_GAP (128*1024*1024UL) +#define MAX_GAP ((TASK_SIZE)/6*5) +#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) static int mmap_is_legacy(struct rlimit *rlim_stack) { @@ -35,6 +36,15 @@ static int mmap_is_legacy(struct rlimit static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) { 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) gap = MIN_GAP; _ Patches currently in -mm which might be from alex@xxxxxxxx are mm-fs-move-randomize_stack_top-from-fs-to-mm.patch arm64-make-use-of-is_compat_task-instead-of-hardcoding-this-test.patch arm64-consider-stack-randomization-for-mmap-base-only-when-necessary.patch arm64-mm-move-generic-mmap-layout-functions-to-mm.patch arm64-mm-make-randomization-selected-by-generic-topdown-mmap-layout.patch arm-properly-account-for-stack-randomization-and-stack-guard-gap.patch arm-use-stack_top-when-computing-mmap-base-address.patch arm-use-generic-mmap-top-down-layout-and-brk-randomization.patch mips-properly-account-for-stack-randomization-and-stack-guard-gap.patch mips-use-stack_top-when-computing-mmap-base-address.patch mips-adjust-brk-randomization-offset-to-fit-generic-version.patch mips-replace-arch-specific-way-to-determine-32bit-task-with-generic-version.patch mips-use-generic-mmap-top-down-layout-and-brk-randomization.patch riscv-make-mmap-allocation-top-down-by-default.patch