linux-kernel - [PATCH 4.14 26/39] sctp: account stream padding length for reconf chunk

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Message-Id: <20211018132326.282921923@linuxfoundation.org>
Date:   Mon, 18 Oct 2021 15:24:35 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vlad Yasevich <vyasevich@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        Eiichi Tsukata <eiichi.tsukata@...anix.com>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Marcelo Ricardo Leitner <mleitner@...hat.com>,
        Xin Long <lucien.xin@...il.com>,
        Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH 4.14 26/39] sctp: account stream padding length for reconf chunk

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

commit a2d859e3fc97e79d907761550dbc03ff1b36479c 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@...il.com>
Cc: Neil Horman <nhorman@...driver.com>
Cc: Greg KH <gregkh@...uxfoundation.org>
Fixes: cc16f00f6529 ("sctp: add support for generating stream reconf ssn reset request chunk")
Reported-by: Eiichi Tsukata <eiichi.tsukata@...anix.com>
Signed-off-by: Eiichi Tsukata <eiichi.tsukata@...anix.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Signed-off-by: Marcelo Ricardo Leitner <mleitner@...hat.com>
Reviewed-by: Xin Long <lucien.xin@...il.com>
Link: https://lore.kernel.org/r/b97c1f8b0c7ff79ac4ed206fc2c49d3612e0850c.1634156849.git.mleitner@redhat.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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
@@ -3623,7 +3623,7 @@ 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;