Re: [PATCH V4 1/2] ptr_ring: fail early if queue occupies more than KMALLOC_MAX_SIZE
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From: Eric Biggers <hidden>
Date: 2018-02-10 19:32:07
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Hi Jason, On Fri, Feb 09, 2018 at 05:45:49PM +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 Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers") 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..6051a5f 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 * sizeof(void *) > KMALLOC_MAX_SIZE) + return NULL;
Are you sure that size can't be over 0x40000000? The proper way to write this (safe from integer overflow) would be: if (size > KMALLOC_MAX_SIZE / sizeof(void *)) return NULL; - Eric