| From foo@baz Tue Aug 8 16:51:58 PDT 2017 |
| From: Xin Long <lucien.xin@gmail.com> |
| Date: Wed, 26 Jul 2017 16:24:59 +0800 |
| Subject: sctp: fix the check for _sctp_walk_params and _sctp_walk_errors |
| |
| From: Xin Long <lucien.xin@gmail.com> |
| |
| |
| [ Upstream commit 6b84202c946cd3da3a8daa92c682510e9ed80321 ] |
| |
| Commit b1f5bfc27a19 ("sctp: don't dereference ptr before leaving |
| _sctp_walk_{params, errors}()") tried to fix the issue that it |
| may overstep the chunk end for _sctp_walk_{params, errors} with |
| 'chunk_end > offset(length) + sizeof(length)'. |
| |
| But it introduced a side effect: When processing INIT, it verifies |
| the chunks with 'param.v == chunk_end' after iterating all params |
| by sctp_walk_params(). With the check 'chunk_end > offset(length) |
| + sizeof(length)', it would return when the last param is not yet |
| accessed. Because the last param usually is fwdtsn supported param |
| whose size is 4 and 'chunk_end == offset(length) + sizeof(length)' |
| |
| This is a badly issue even causing sctp couldn't process 4-shakes. |
| Client would always get abort when connecting to server, due to |
| the failure of INIT chunk verification on server. |
| |
| The patch is to use 'chunk_end <= offset(length) + sizeof(length)' |
| instead of 'chunk_end < offset(length) + sizeof(length)' for both |
| _sctp_walk_params and _sctp_walk_errors. |
| |
| Fixes: b1f5bfc27a19 ("sctp: don't dereference ptr before leaving _sctp_walk_{params, errors}()") |
| Signed-off-by: Xin Long <lucien.xin@gmail.com> |
| Acked-by: Neil Horman <nhorman@tuxdriver.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| include/net/sctp/sctp.h | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/include/net/sctp/sctp.h |
| +++ b/include/net/sctp/sctp.h |
| @@ -444,7 +444,7 @@ _sctp_walk_params((pos), (chunk), ntohs( |
| |
| #define _sctp_walk_params(pos, chunk, end, member)\ |
| for (pos.v = chunk->member;\ |
| - (pos.v + offsetof(struct sctp_paramhdr, length) + sizeof(pos.p->length) <\ |
| + (pos.v + offsetof(struct sctp_paramhdr, length) + sizeof(pos.p->length) <=\ |
| (void *)chunk + end) &&\ |
| pos.v <= (void *)chunk + end - ntohs(pos.p->length) &&\ |
| ntohs(pos.p->length) >= sizeof(sctp_paramhdr_t);\ |
| @@ -456,7 +456,7 @@ _sctp_walk_errors((err), (chunk_hdr), nt |
| #define _sctp_walk_errors(err, chunk_hdr, end)\ |
| for (err = (sctp_errhdr_t *)((void *)chunk_hdr + \ |
| sizeof(sctp_chunkhdr_t));\ |
| - ((void *)err + offsetof(sctp_errhdr_t, length) + sizeof(err->length) <\ |
| + ((void *)err + offsetof(sctp_errhdr_t, length) + sizeof(err->length) <=\ |
| (void *)chunk_hdr + end) &&\ |
| (void *)err <= (void *)chunk_hdr + end - ntohs(err->length) &&\ |
| ntohs(err->length) >= sizeof(sctp_errhdr_t); \ |