linux-kernel - [PATCH v2 2/5] scsi: BusLogic: Avoid unbounded `vsprintf' use

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Message-ID: <alpine.DEB.2.21.2104201939390.44318@angie.orcam.me.uk>
Date:   Tue, 20 Apr 2021 20:01:52 +0200 (CEST)
From:   "Maciej W. Rozycki" <macro@...am.me.uk>
To:     Khalid Aziz <khalid@...ehiking.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
cc:     Christoph Hellwig <hch@....de>, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/5] scsi: BusLogic: Avoid unbounded `vsprintf' use

Existing `blogic_msg' invocations do not appear to overrun its internal 
buffer of a fixed length of 100, which would cause stack corruption, but 
it's easy to miss with possible further updates and a fix is cheap in 
performance terms, so limit the output produced into the buffer by using 
`vscnprintf' rather than `vsprintf'.

Signed-off-by: Maciej W. Rozycki <macro@...am.me.uk>
---
Changes from v1:

- use `vscnprintf' instead of `vsnprintf' for the correct character count.
---
 drivers/scsi/BusLogic.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

linux-buslogic-vscnprintf.diff
Index: linux-macro-ide/drivers/scsi/BusLogic.c
===================================================================
--- linux-macro-ide.orig/drivers/scsi/BusLogic.c
+++ linux-macro-ide/drivers/scsi/BusLogic.c
@@ -3588,7 +3588,7 @@ static void blogic_msg(enum blogic_msgle
 	int len = 0;
 
 	va_start(args, adapter);
-	len = vsprintf(buf, fmt, args);
+	len = vscnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 	if (msglevel == BLOGIC_ANNOUNCE_LEVEL) {
 		static int msglines = 0;