From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Date: Sat, 19 Sep 2020 02:05:49 +0000 Subject: Re: [PATCH v2] net: sctp: Fix IPv6 ancestor_size calc in sctp_copy_descendant Message-Id: <20200919020549.GA70998@localhost.localdomain> List-Id: References: <20200918132957.GB82043@localhost.localdomain> <20200919001211.355148-1-hptasinski@google.com> In-Reply-To: <20200919001211.355148-1-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 Sat, Sep 19, 2020 at 12:12:11AM +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. > > Fixes: 636d25d557d1 ("sctp: not copy sctp_sock pd_lobby in sctp_copy_descendant") > Signed-off-by: Henry Ptasinski Acked-by: Marcelo Ricardo Leitner ... > { > - int ancestor_size = sizeof(struct inet_sock) + > - sizeof(struct sctp_sock) - > - offsetof(struct sctp_sock, pd_lobby); > - > - if (sk_from->sk_family = PF_INET6) > - ancestor_size += sizeof(struct ipv6_pinfo); > + size_t ancestor_size = sizeof(struct inet_sock); > > + ancestor_size += sk_from->sk_prot->obj_size; Heh, of course. Nice one. > + ancestor_size -= offsetof(struct sctp_sock, pd_lobby); > __inet_sk_copy_descendant(sk_to, sk_from, ancestor_size); > } > > -- > 2.28.0.681.g6f77f65b4e-goog >