diff options
| author | Helge Deller <deller@gmx.de> | 2023-11-13 11:12:57 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-11-15 15:30:09 -0800 |
| commit | 5f74f820f6fc844b95f9e5e406e0a07d97510420 (patch) | |
| tree | 852011007780addec07154b8463f69f9b9dcefea /mm | |
| parent | 13b2a4b22e98ff80b888a160a2acd92d81b05925 (diff) | |
parisc: fix mmap_base calculation when stack grows upwards
Matoro reported various userspace crashes on the parisc platform with kernel
6.6 and bisected it to commit 3033cd430768 ("parisc: Use generic mmap top-down
layout and brk randomization").
That commit switched parisc to use the common infrastructure to calculate
mmap_base, but missed that the mmap_base() function takes care for
architectures where the stack grows downwards only.
Fix the mmap_base() calculation to include the stack-grows-upwards case
and thus fix the userspace crashes on parisc.
Link: https://lkml.kernel.org/r/ZVH2qeS1bG7/1J/l@p100
Fixes: 3033cd430768 ("parisc: Use generic mmap top-down layout and brk randomization")
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: matoro <matoro_mailinglist_kernel@matoro.tk>
Tested-by: matoro <matoro_mailinglist_kernel@matoro.tk>
Cc: <stable@vger.kernel.org> [6.6+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/util.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/mm/util.c b/mm/util.c index aa01f6ea5a75..744b4d7e3fae 100644 --- a/mm/util.c +++ b/mm/util.c @@ -414,6 +414,15 @@ static int mmap_is_legacy(struct rlimit *rlim_stack) static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) { +#ifdef CONFIG_STACK_GROWSUP + /* + * For an upwards growing stack the calculation is much simpler. + * Memory for the maximum stack size is reserved at the top of the + * task. mmap_base starts directly below the stack and grows + * downwards. + */ + return PAGE_ALIGN_DOWN(mmap_upper_limit(rlim_stack) - rnd); +#else unsigned long gap = rlim_stack->rlim_cur; unsigned long pad = stack_guard_gap; @@ -431,6 +440,7 @@ static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) gap = MAX_GAP; return PAGE_ALIGN(STACK_TOP - gap - rnd); +#endif } void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) |