Re: [PATCH v1] io_uring: fix dangling iovec after provided-buffer bundle grow failure

[Hao-Yu Yang]

On Mon, Jul 06, 2026 at 11:39:14AM -0600, Jens Axboe wrote:
> On 7/6/26 11:34 AM, Hao-Yu Yang wrote:
> > On Mon, Jul 06, 2026 at 11:13:55AM -0600, Jens Axboe wrote:
> >> On 7/6/26 11:01 AM, Hao-Yu Yang wrote:
> >>> Sorry, i forgot to cc others mail
> >>>
> >>> I discovered and wrote the PoC myself. Trigger way is
> >>>  send1: Submit an IORING_OP_SEND request with four valid
> >>>  provided buffers. The system will allocate and cache an
> >>>  iovec array (of size 4) for this request and store the
> >>>  pointer in kmsg->vec.iovec.
> >>>
> >>>  send2: Submit a second send request with 8, and I set
> >>>  the fourth passed-in address to point to an invalid address.
> >>>  Now kmsg still hold old iovec, but old iovec object have
> >>>  been freed.
> >>>
> >>>  So this will lead dangling pointer.
> >>
> >> Side note: please don't top post, linux mailing lists always reply
> >> under the text for better readability. Top posting turns any kind
> >> of threaded conversation into both a mess, and it's also wasteful.
> >>
> >> Great thanks! Want to turn this into a liburing test case? Then we can
> >> include it there as well, and it'd catch both UAF and memory leaks when
> >> run.
> >>
> >> -- 
> >> Jens Axboe
> > 
> > How to turn this into a liburing test case? Should this be included in
> > the v2 patch?
> 
> Look at the tests in test/ in liburing. Or just send the reproducer and
> I can get it turned into a test case.
> 
> Should be separate from a kernel patch, it's a patch for an entirely
> different repository.
> 
> 
> -- 
> Jens Axboe

OK, I will send v2 patch first when i wake up. And I now my PoC to trigger this KASAN have became a exploit can use to priviledge escalation.
I think i should send this script to your email? (not included any public gmail?)