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net: sctp: Fix IPv6 ancestor_size calc in sctp_copy_descendant

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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: 636d25d557 ("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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Henry Ptasinski 2020-09-19 00:12:11 +00:00 • committed by David S. Miller
parent b6e11785cf
commit fe81d9f618
2 changed files with 8 additions and 9 deletions
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8
include/net/sctp/structs.h
View file

@ -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;
};

9
net/sctp/socket.c
View file

@ -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);
}