Martin KaFai Lau wrote:
> On 1/2/24 4:00 AM, Jakub Sitnicki wrote:
> > On Thu, Dec 21, 2023 at 03:23 PM -08, John Fastabend wrote:
> >> When sockets are added to a sockmap or sockhash we allocate and init a
> >> psock. Then update the proto ops with sock_map_init_proto the flow is
> >>
> >> sock_hash_update_common
> >> sock_map_link
> >> psock = sock_map_psock_get_checked() <-returns existing psock
> >> sock_map_init_proto(sk, psock) <- updates sk_proto
> >>
> >> If the socket is already in a map this results in the sock_map_init_proto
> >> being called multiple times on the same socket. We do this because when
> >> a socket is added to multiple maps this might result in a new set of BPF
> >> programs being attached to the socket requiring an updated ops struct.
> >>
> >> This creates a rule where it must be safe to call psock_update_sk_prot
> >> multiple times. When we added a fix for UAF through unix sockets in patch
> >> 4dd9a38a753fc we broke this rule by adding a sock_hold in that path
> >> to ensure the sock is not released. The result is if a af_unix stream sock
> >> is placed in multiple maps it results in a memory leak because we call
> >> sock_hold multiple times with only a single sock_put on it.
> >>
> >> Fixes: 4dd9a38a753fc ("bpf: sockmap, fix proto update hook to avoid dup calls")
>
> The Fixes tag looks wrong ;)
>
> I changed it to
>
> Fixes: 8866730aed51 ("bpf, sockmap: af_unix stream sockets need to hold ref for
> pair sock")
>
> >> Rebported-by: Xingwei Lee <xrivendell7@xxxxxxxxx>
> >
> > Nit: Typo ^
>
> yep. fixed.
>
> Also added the missing "test_sockmap_pass_prog__destroy(skel)" to the
> sockmap_basic.c selftest.
Thanks! Appreciate it Martin.
>
> Applied. Thanks for the fixes and the review.
>
