From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Date: Fri, 18 Sep 2020 13:29:57 +0000 Subject: Re: [PATCH] net: sctp: Fix IPv6 ancestor_size calc in sctp_copy_descendant Message-Id: <20200918132957.GB82043@localhost.localdomain> List-Id: References: <20200918015610.3596417-1-hptasinski@google.com> In-Reply-To: <20200918015610.3596417-1-hptasinski@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Henry Ptasinski Cc: linux-sctp@vger.kernel.org, netdev@vger.kernel.org, Vlad Yasevich , Neil Horman , "David S . Miller" , Jakub Kicinski , Corey Minyard On Fri, Sep 18, 2020 at 01:56:10AM +0000, Henry Ptasinski wrote: > When calculating ancestor_size with IPv6 enabled, simply using > sizeof(struct ipv6_pinfo) doesn't account for extra bytes needed for > alignment in the struct sctp6_sock. On x86, there aren't any extra > bytes, but on ARM the ipv6_pinfo structure is aligned on an 8-byte > boundary so there were 4 pad bytes that were omitted from the > ancestor_size calculation. This would lead to corruption of the > pd_lobby pointers, causing an oops when trying to free the sctp > structure on socket close. Makes sense. > > Signed-off-by: Henry Ptasinski Please add a: Fixes: 636d25d557d1 ("sctp: not copy sctp_sock pd_lobby in sctp_copy_descendant") > --- > net/sctp/socket.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > index 836615f71a7d..a6358c81f087 100644 > --- a/net/sctp/socket.c > +++ b/net/sctp/socket.c > @@ -9220,12 +9220,14 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk, > static inline void sctp_copy_descendant(struct sock *sk_to, ^^^^^^ I'll send a patch to fix/remove this. > const struct sock *sk_from) > { > - int ancestor_size = sizeof(struct inet_sock) + > - sizeof(struct sctp_sock) - > - offsetof(struct sctp_sock, pd_lobby); ^^^^^^^^ Then, as this patch is actually fixing the aforementioned commit, please also update the comment on sctp_sock definition, as pd_lobby now is also skipped. > + size_t ancestor_size = sizeof(struct inet_sock); > > if (sk_from->sk_family = PF_INET6) > - ancestor_size += sizeof(struct ipv6_pinfo); > + ancestor_size += sizeof(struct sctp6_sock); As you probably noticed by the build bot email already, there need to be some protection to building without IPv6 enabled. To avoid ifdefs here, something similar to how inet_sk_copy_descendant() is done is probably welcomed, but please feel free to be creative. :-) > + else > + ancestor_size += sizeof(struct sctp_sock); > + > + ancestor_size -= offsetof(struct sctp_sock, pd_lobby); > > __inet_sk_copy_descendant(sk_to, sk_from, ancestor_size); > } > -- > 2.28.0.681.g6f77f65b4e-goog >