sctp: account stream padding length for reconf chunk

stable inclusion
from stable-5.10.75
commit d84a69ac410f6228873d05d35120f6bdddab7fc3
bugzilla: 182987 https://gitee.com/openeuler/kernel/issues/I4I3MP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d84a69ac410f6228873d05d35120f6bdddab7fc3

--------------------------------

commit a2d859e3 upstream.

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: cc16f00f ("sctp: add support for generating stream reconf ssn reset request chunk")
Reported-by: NEiichi Tsukata <eiichi.tsukata@nutanix.com>
Signed-off-by: NEiichi Tsukata <eiichi.tsukata@nutanix.com>
Signed-off-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: NMarcelo Ricardo Leitner <mleitner@redhat.com>
Reviewed-by: NXin Long <lucien.xin@gmail.com>
Link: https://lore.kernel.org/r/b97c1f8b0c7ff79ac4ed206fc2c49d3612e0850c.1634156849.git.mleitner@redhat.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/sctp/sm_make_chunk.c

@@ -3651,7 +3651,7 @@ 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;