Messages in this thread | | | From | Alex Ghiti <> | Subject | Re: [PATCH v3 08/11] mips: Properly account for stack randomization and stack guard gap | Date | Fri, 19 Apr 2019 09:20:01 +0200 |
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On 4/18/19 5:27 PM, Paul Burton wrote: > Hi Alexandre, > > On Wed, Apr 17, 2019 at 01:22:44AM -0400, Alexandre Ghiti wrote: >> 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 mips here: >> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1429066.html >> >> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> > For patches 8-10: > > Acked-by: Paul Burton <paul.burton@mips.com> > > Thanks for improving this,
Thank you for your time,
Alex
> Paul > >> --- >> arch/mips/mm/mmap.c | 14 ++++++++++++-- >> 1 file changed, 12 insertions(+), 2 deletions(-) >> >> diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c >> index 2f616ebeb7e0..3ff82c6f7e24 100644 >> --- a/arch/mips/mm/mmap.c >> +++ b/arch/mips/mm/mmap.c >> @@ -21,8 +21,9 @@ unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */ >> EXPORT_SYMBOL(shm_align_mask); >> >> /* 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) >> { >> @@ -38,6 +39,15 @@ static int mmap_is_legacy(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 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; >> -- >> 2.20.1 >> > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
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