On 2018年01月25日 21:45, Michael S. Tsirkin wrote:
On Thu, Jan 25, 2018 at 03:31:42PM +0800, Jason Wang wrote: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:[email protected] Cc: John Fastabend<[email protected]> Signed-off-by: Jason Wang<[email protected]>Ugh that's just way too ugly. I'll work on dropping the extra + 1 - but calling this function with -1 size is the real source of the bug. Do you know how come we do that?
It looks e.g try to change tx_queue_len to UINT_MAX. And we probably can't prevent user form trying to do this?
Thanks
