Messages in this thread Patch in this message | | | From | Jason Wang <> | Subject | [PATCH net-next] ptr_ring: fix integer overflow | Date | Thu, 25 Jan 2018 15:31:42 +0800 |
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We try to allocate one more entry for lockless peeking. The adding operation may overflow which causes zero to be passed to kmalloc(). In this case, it returns ZERO_SIZE_PTR without any notice by ptr ring. Try to do producing or consuming on such ring will lead NULL dereference. Fix this detect and fail early.
Fixes: bcecb4bbf88a ("net: ptr_ring: otherwise safe empty checks can overrun array bounds") Reported-by: syzbot+87678bcf753b44c39b67@syzkaller.appspotmail.com Cc: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Jason Wang <jasowang@redhat.com> --- 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 9ca1726..3f99484 100644 --- a/include/linux/ptr_ring.h +++ b/include/linux/ptr_ring.h @@ -453,6 +453,8 @@ 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 (unlikely(size + 1 == 0)) + return NULL; /* Allocate an extra dummy element at end of ring to avoid consumer head * or produce head access past the end of the array. Possible when * producer/consumer operations and __ptr_ring_peek operations run in -- 2.7.4
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