linux-kernel - [PATCH v2] scsi: pm80xx: Use C String API for string comparisons

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Message-Id: <20250312200532.it.808-kees@kernel.org>
Date: Wed, 12 Mar 2025 13:05:36 -0700
From: Kees Cook <kees@...nel.org>
To: Jack Wang <jinpu.wang@...ud.ionos.com>
Cc: Kees Cook <kees@...nel.org>,
	"James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH v2] scsi: pm80xx: Use C String API for string comparisons

When a character array without a terminating NUL character has a static
initializer, GCC 15's -Wunterminated-string-initialization will only
warn if the array lacks the "nonstring" attribute[1]. There is no reason
for the command lookup logic to not use strcmp(), so grow the string
length and update the check to eliminate the warning:

../drivers/scsi/pm8001/pm8001_ctl.c:652:7: warning: initializer-string for array of 'unsigned char' truncates NUL terminator but destination lacks 'nonstring' attribute (9 chars into 8 available) [-Wunterminated-string-initialization]
  652 |      {"set_nvmd",    FLASH_CMD_SET_NVMD},
      |       ^~~~~~~~~~

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1]
Signed-off-by: Kees Cook <kees@...nel.org>
---
In taking another look at this, I realize that actually strcmp() should be used,
so just grow the size of this character array and use strcmp().
 v1: https://lore.kernel.org/lkml/20250310222553.work.437-kees@kernel.org/
 v2: Use strcmp()
---
Cc: Jack Wang <jinpu.wang@...ud.ionos.com>
Cc: "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>
Cc: "Martin K. Petersen" <martin.petersen@...cle.com>
Cc: linux-scsi@...r.kernel.org
---
 drivers/scsi/pm8001/pm8001_ctl.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/pm8001/pm8001_ctl.c b/drivers/scsi/pm8001/pm8001_ctl.c
index 85ff95c6543a..bb8fd5f0f441 100644
--- a/drivers/scsi/pm8001/pm8001_ctl.c
+++ b/drivers/scsi/pm8001/pm8001_ctl.c
@@ -644,7 +644,7 @@ static DEVICE_ATTR(gsm_log, S_IRUGO, pm8001_ctl_gsm_log_show, NULL);
 #define FLASH_CMD_SET_NVMD    0x02
 
 struct flash_command {
-     u8      command[8];
+     u8      command[9];
      int     code;
 };
 
@@ -825,8 +825,7 @@ static ssize_t pm8001_store_update_fw(struct device *cdev,
 	}
 
 	for (i = 0; flash_command_table[i].code != FLASH_CMD_NONE; i++) {
-		if (!memcmp(flash_command_table[i].command,
-				 cmd_ptr, strlen(cmd_ptr))) {
+		if (!strcmp(flash_command_table[i].command, cmd_ptr)) {
 			flash_command = flash_command_table[i].code;
 			break;
 		}
-- 
2.34.1