| Message ID | 20200919001211.355148-1-hptasinski@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] net: sctp: Fix IPv6 ancestor_size calc in sctp_copy_descendant | expand |
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 <hptasinski@google.com> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> ... > { > - 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 >
From: Henry Ptasinski <hptasinski@google.com> Date: Sat, 19 Sep 2020 00:12:11 +0000 > 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 <hptasinski@google.com> Applied and queued up for -stable, thank you.
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h index b33f1aefad09..0bdff38eb4bb 100644 --- a/include/net/sctp/structs.h +++ b/include/net/sctp/structs.h @@ -226,12 +226,14 @@ struct sctp_sock { data_ready_signalled:1; atomic_t pd_mode; + + /* Fields after this point will be skipped on copies, like on accept + * and peeloff operations + */ + /* Receive to here while partial delivery is in effect. */ struct sk_buff_head pd_lobby; - /* These must be the last fields, as they will skipped on copies, - * like on accept and peeloff operations - */ struct list_head auto_asconf_list; int do_auto_asconf; }; diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 836615f71a7d..53d0a4161df3 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -9220,13 +9220,10 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk, static inline void sctp_copy_descendant(struct sock *sk_to, const struct sock *sk_from) { - 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; + ancestor_size -= offsetof(struct sctp_sock, pd_lobby); __inet_sk_copy_descendant(sk_to, sk_from, ancestor_size); }
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 <hptasinski@google.com> --- include/net/sctp/structs.h | 8 +++++--- net/sctp/socket.c | 9 +++------ 2 files changed, 8 insertions(+), 9 deletions(-)