linux-kernel - [PATCH] scsi: target: Replace strlcpy with strscpy

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Message-ID: <20230830200717.4129442-1-azeemshaikh38@gmail.com>
Date:   Wed, 30 Aug 2023 20:07:17 +0000
From:   Azeem Shaikh <azeemshaikh38@...il.com>
To:     "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     linux-hardening@...r.kernel.org,
        Azeem Shaikh <azeemshaikh38@...il.com>,
        linux-scsi@...r.kernel.org, target-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] scsi: target: Replace strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

Direct replacement is safe here since return value of -errno
is used to check for truncation instead of sizeof(dest).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
---
 drivers/target/target_core_configfs.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 936e5ff1b209..b3d2c14e2ea9 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -1392,16 +1392,15 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item,
 	/* +2 to allow for a trailing (stripped) '\n' and null-terminator */
 	unsigned char buf[INQUIRY_VENDOR_LEN + 2];
 	char *stripped = NULL;
-	size_t len;
+	ssize_t len;
 	ssize_t ret;

-	len = strlcpy(buf, page, sizeof(buf));
-	if (len < sizeof(buf)) {
+	len = strscpy(buf, page, sizeof(buf));
+	if (len > 0) {
 		/* Strip any newline added from userspace. */
 		stripped = strstrip(buf);
-		len = strlen(stripped);
 	}
-	if (len > INQUIRY_VENDOR_LEN) {
+	if (len < 0 || strlen(stripped) > INQUIRY_VENDOR_LEN) {
 		pr_err("Emulated T10 Vendor Identification exceeds"
 			" INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN)
 			"\n");
--
2.42.0.283.g2d96d420d3-goog