Re: [PATCH net] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2018-02-08 15:44:51
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On Wed, Feb 07, 2018 at 04:08:25PM +0800, Jason Wang wrote:
quoted hunk ↗ jump to hunk
To avoid slab to warn about exceeded size, fail early if queue occupies more than KMALLOC_MAX_SIZE. Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com Signed-off-by: Jason Wang <redacted> --- include/linux/ptr_ring.h | 2 ++ 1 file changed, 2 insertions(+)diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h index 1883d61..4b862da 100644 --- a/include/linux/ptr_ring.h +++ b/include/linux/ptr_ring.h@@ -466,6 +466,8 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r, static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp) { + if (size > KMALLOC_MAX_SIZE) + return NULL; return kcalloc(size, sizeof(void *), gfp); }
I guess this approach does begin to make more sense at least as a temporary stop-gap. But does this actually prevent the crash in all cases? size is in void* entry units, KMALLOC_MAX_SIZE is in bytes.
-- 2.7.4