Messages in this thread Patch in this message | | | From | Walter Wu <> | Subject | [PATCH v3] lib/stackdepot: Fix global out-of-bounds in stackdepot | Date | Thu, 30 Jan 2020 14:44:30 +0800 |
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If the depot_index = STACK_ALLOC_MAX_SLABS - 2 and next_slab_inited = 0, then it will cause array out-of-bounds access, so that we should modify the detection to avoid this array out-of-bounds bug.
Assume depot_index = STACK_ALLOC_MAX_SLABS - 3 Consider following call flow sequence:
stack_depot_save() depot_alloc_stack() if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) //pass depot_index++ //depot_index = STACK_ALLOC_MAX_SLABS - 2 if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) //enter smp_store_release(&next_slab_inited, 0); //next_slab_inited = 0 init_stack_slab() if (stack_slabs[depot_index] == NULL) //enter and exit
stack_depot_save() depot_alloc_stack() if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) //pass depot_index++ //depot_index = STACK_ALLOC_MAX_SLABS - 1 init_stack_slab(&prealloc) stack_slabs[depot_index + 1] //here get global out-of-bounds
Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Alexander Potapenko <glider@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Kate Stewart <kstewart@linuxfoundation.org> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com> --- changes in v2: modify call flow sequence and preconditon
changes in v3: add some reviewers --- lib/stackdepot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/stackdepot.c b/lib/stackdepot.c index ed717dd08ff3..7e8a15e41600 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -106,7 +106,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size, required_size = ALIGN(required_size, 1 << STACK_ALLOC_ALIGN); if (unlikely(depot_offset + required_size > STACK_ALLOC_SIZE)) { - if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) { + if (unlikely(depot_index + 2 >= STACK_ALLOC_MAX_SLABS)) { WARN_ONCE(1, "Stack depot reached limit capacity"); return NULL; } -- 2.18.0 | |