Messages in this thread | | | From | Eric Dumazet <> | Date | Fri, 31 Mar 2023 09:04:47 +0200 | Subject | Re: general protection fault in raw_seq_start |
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On Thu, Mar 30, 2023 at 11:55 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
> Thanks for reporting the issue. > > It seems we need to use RCU variant in raw_get_first(). > I'll post a patch. > > --- > diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c > index 3cf68695b40d..fe0d1ad20b35 100644 > --- a/net/ipv4/raw.c > +++ b/net/ipv4/raw.c > @@ -957,7 +957,7 @@ static struct sock *raw_get_first(struct seq_file *seq, int bucket) > for (state->bucket = bucket; state->bucket < RAW_HTABLE_SIZE; > ++state->bucket) { > hlist = &h->ht[state->bucket]; > - sk_nulls_for_each(sk, hnode, hlist) { > + sk_nulls_for_each_rcu(sk, hnode, hlist) { > if (sock_net(sk) == seq_file_net(seq)) > return sk; >
No, we do not want this. You missed that sk_nulls_for_each_rcu() needs a specific protocol (see Documentation/RCU/rculist_nulls.rst for details)
RCU is needed in the data path, not for this control path.
My patch went too far in the RCU conversion. I did not think about syzbot harassing /proc files :)
We need raw_seq_start and friends to go back to use the lock.
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