sctp: account stream padding length for reconf chunk

sctp_make_strreset_req() makes repeated calls to sctp_addto_chunk()
which will automatically account for padding on each call. inreq and
outreq are already 4 bytes aligned, but the payload is not and doing
SCTP_PAD4(a + b) (which _sctp_make_chunk() did implicitly here) is
different from SCTP_PAD4(a) + SCTP_PAD4(b) and not enough. It led to
possible attempt to use more buffer than it was allocated and triggered
a BUG_ON.

Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Fixes: cc16f00f6529 ("sctp: add support for generating stream reconf ssn reset request chunk")
Reported-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com>
Signed-off-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Link: https://lore.kernel.org/r/b97c1f8b0c7ff79ac4ed206fc2c49d3612e0850c.1634156849.git.mleitner@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index b8fa8f1a727704df07e78c0b72e77a4ecdd76b76..c7503fd6491593fc749b9af182c646a39ed2ddbc 100644 (file)
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -3697,7 +3697,7 @@ struct sctp_chunk *sctp_make_strreset_req(
        outlen = (sizeof(outreq) + stream_len) * out;
        inlen = (sizeof(inreq) + stream_len) * in;
 
-       retval = sctp_make_reconf(asoc, outlen + inlen);
+       retval = sctp_make_reconf(asoc, SCTP_PAD4(outlen) + SCTP_PAD4(inlen));
        if (!retval)
                return NULL;