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From:   Arnd Bergmann <arnd@kernel.org>
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Subject: [PATCH 09/11] scsi: lpfc: fix gcc -Wstringop-overread warning
Date:   Mon, 22 Mar 2021 17:02:47 +0100
Message-Id: <20210322160253.4032422-10-arnd@kernel.org>
In-Reply-To: <20210322160253.4032422-1-arnd@kernel.org>
References: <20210322160253.4032422-1-arnd@kernel.org>
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From: Arnd Bergmann <arnd@arndb.de>

gcc-11 warns about an strnlen with a length larger than the size of the
passed buffer:

drivers/scsi/lpfc/lpfc_attr.c: In function 'lpfc_nvme_info_show':
drivers/scsi/lpfc/lpfc_attr.c:518:25: error: 'strnlen' specified bound 4095 exceeds source size 24 [-Werror=stringop-overread]
  518 |                         strnlen(LPFC_NVME_INFO_MORE_STR, PAGE_SIZE - 1)
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In this case, the code is entirely valid, as the string is properly
terminated, and the size argument is only there out of extra caution
in case it exceeds a page.

This cannot really happen here, so just simplify it to a sizeof().

Fixes: afff0d2321ea ("scsi: lpfc: Add Buffer overflow check, when nvme_info larger than PAGE_SIZE")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/scsi/lpfc/lpfc_attr.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c
index bdd9a29f4201..f6d886f9dfb3 100644
--- a/drivers/scsi/lpfc/lpfc_attr.c
+++ b/drivers/scsi/lpfc/lpfc_attr.c
@@ -512,11 +512,9 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
 				"6314 Catching potential buffer "
 				"overflow > PAGE_SIZE = %lu bytes\n",
 				PAGE_SIZE);
-		strlcpy(buf + PAGE_SIZE - 1 -
-			strnlen(LPFC_NVME_INFO_MORE_STR, PAGE_SIZE - 1),
+		strlcpy(buf + PAGE_SIZE - 1 - sizeof(LPFC_NVME_INFO_MORE_STR),
 			LPFC_NVME_INFO_MORE_STR,
-			strnlen(LPFC_NVME_INFO_MORE_STR, PAGE_SIZE - 1)
-			+ 1);
+			sizeof(LPFC_NVME_INFO_MORE_STR) + 1);
 	}
 
 	return len;
-- 
2.29.2