Messages in this thread | | | Subject | Re: [PATCH net-next] ptr_ring: fix integer overflow | From | Jason Wang <> | Date | Thu, 25 Jan 2018 22:17:38 +0800 |
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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:syzbot+87678bcf753b44c39b67@syzkaller.appspotmail.com >> Cc: John Fastabend<john.fastabend@gmail.com> >> Signed-off-by: Jason Wang<jasowang@redhat.com> > 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
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