From: Eiichi Tsukata <eiichi.tsukata@nutanix.com>

Date: Wed, 13 Oct 2021 17:27:29 -0300

Subject: sctp: account stream padding length for reconf chunk

Patch-mainline: v5.15-rc6

Git-commit: a2d859e3fc97e79d907761550dbc03ff1b36479c

References: bsc#1194985 CVE-2022-0322

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>

Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>

---

 net/sctp/sm_make_chunk.c |    2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/sctp/sm_make_chunk.c

+++ b/net/sctp/sm_make_chunk.c

@@ -3647,7 +3647,7 @@ struct sctp_chunk *sctp_make_strreset_re

 	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;