linux-hardening - [PATCH 08/10] scsi: aic7xxx: aicasm: Replace snprintf() with the safer scnprintf() variant

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Date: Thu,  8 Feb 2024 08:44:20 +0000
From: Lee Jones <lee@...nel.org>
To: lee@...nel.org
Cc: linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org,
	Hannes Reinecke <hare@...e.com>,
	"James E.J. Bottomley" <jejb@...ux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	linux-scsi@...r.kernel.org
Subject: [PATCH 08/10] scsi: aic7xxx: aicasm: Replace snprintf() with the safer scnprintf() variant

There is a general misunderstanding amongst engineers that {v}snprintf()
returns the length of the data *actually* encoded into the destination
array.  However, as per the C99 standard {v}snprintf() really returns
the length of the data that *would have been* written if there were
enough space for it.  This misunderstanding has led to buffer-overruns
in the past.  It's generally considered safer to use the {v}scnprintf()
variants in their place (or even sprintf() in simple cases).  So let's
do that.

Link: https://lwn.net/Articles/69419/
Link: https://github.com/KSPP/linux/issues/105
Signed-off-by: Lee Jones <lee@...nel.org>
---
Cc: Hannes Reinecke <hare@...e.com>
Cc: "James E.J. Bottomley" <jejb@...ux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@...cle.com>
Cc: Lee Jones <lee@...nel.org>
Cc: linux-scsi@...r.kernel.org
---
 drivers/scsi/aic7xxx/aicasm/aicasm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/aic7xxx/aicasm/aicasm.c b/drivers/scsi/aic7xxx/aicasm/aicasm.c
index 8d995186e557a..bc758e78d3c06 100644
--- a/drivers/scsi/aic7xxx/aicasm/aicasm.c
+++ b/drivers/scsi/aic7xxx/aicasm/aicasm.c
@@ -331,7 +331,7 @@ back_patch()
 			if (cur_instr->patch_label->type != LABEL) {
 				char buf[255];
 
-				snprintf(buf, sizeof(buf),
+				scnprintf(buf, sizeof(buf),
 					 "Undefined label %s",
 					 cur_instr->patch_label->name);
 				stop(buf, EX_DATAERR);
-- 
2.43.0.594.gd9cf4e227d-goog