From: Walter Wu <walter-zh.wu@mediatek.com>
To: Dmitry Vyukov <dvyukov@google.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Alexander Potapenko" <glider@google.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
Kate Stewart <kstewart@linuxfoundation.org>
Cc: Walter Wu <walter-zh.wu@mediatek.com>,
linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
wsd_upstream <wsd_upstream@mediatek.com>
Subject: [PATCH v3] lib/stackdepot: Fix global out-of-bounds in stackdepot
Date: Thu, 30 Jan 2020 14:44:30 +0800 [thread overview]
Message-ID: <20200130064430.17198-1-walter-zh.wu@mediatek.com> (raw)
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
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next reply other threads:[~2020-01-30 6:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-30 6:44 Walter Wu [this message]
2020-01-30 12:03 ` [PATCH v3] lib/stackdepot: Fix global out-of-bounds in stackdepot Alexander Potapenko
2020-01-31 2:05 ` Walter Wu
2020-01-31 18:11 ` Alexander Potapenko
2020-02-03 2:05 ` Walter Wu
2020-02-03 10:30 ` Alexander Potapenko
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