[PATCH v2] scsi: target: Replace strlcpy with strscpy

Azeem Shaikh
2023-08-30T21:10:29Z

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@gmail.com>
---
v2:
* Replace all instances of strlcpy in this file instead of just 1.

v1:
* https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/

drivers/target/target_core_configfs.c | 27 ++++++++++++---------------
1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 936e5ff1b209..10a22a428267 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");
@@ -1448,16 +1447,15 @@ static ssize_t target_wwn_product_id_store(struct config_item *item,
/* +2 to allow for a trailing (stripped) '\n' and null-terminator */
unsigned char buf[INQUIRY_MODEL_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_MODEL_LEN) {
+ if (len < 0 || strlen(stripped) > INQUIRY_MODEL_LEN) {
pr_err("Emulated T10 Vendor exceeds INQUIRY_MODEL_LEN: "
__stringify(INQUIRY_MODEL_LEN)
"\n");
@@ -1504,16 +1502,15 @@ static ssize_t target_wwn_revision_store(struct config_item *item,
/* +2 to allow for a trailing (stripped) '\n' and null-terminator */
unsigned char buf[INQUIRY_REVISION_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_REVISION_LEN) {
+ if (len < 0 || strlen(stripped) > INQUIRY_REVISION_LEN) {
pr_err("Emulated T10 Revision exceeds INQUIRY_REVISION_LEN: "
__stringify(INQUIRY_REVISION_LEN)
"\n");
--
2.42.0.283.g2d96d420d3-goog