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authorHelge Deller <deller@gmx.de>2023-11-13 11:12:57 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-11-15 15:30:09 -0800
commit5f74f820f6fc844b95f9e5e406e0a07d97510420 (patch)
tree852011007780addec07154b8463f69f9b9dcefea /mm/util.c
parent13b2a4b22e98ff80b888a160a2acd92d81b05925 (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/util.c')
-rw-r--r--mm/util.c10
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)