[PATCH AUTOSEL 5.10 02/14] crypto: lrw,xts - Replace strlcpy with strscpy

[Sasha Levin]

From: Azeem Shaikh <azeemshaikh38@xxxxxxxxx>

[ Upstream commit babb80b3ecc6f40c962e13c654ebcd27f25ee327 ]

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@xxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 crypto/lrw.c | 6 +++---
 crypto/xts.c | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/crypto/lrw.c b/crypto/lrw.c
index bcf09fbc750af..80d9076e42e0b 100644
--- a/crypto/lrw.c
+++ b/crypto/lrw.c
@@ -357,10 +357,10 @@ static int lrw_create(struct crypto_template *tmpl, struct rtattr **tb)
 	 * cipher name.
 	 */
 	if (!strncmp(cipher_name, "ecb(", 4)) {
-		unsigned len;
+		int len;
 
-		len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
-		if (len < 2 || len >= sizeof(ecb_name))
+		len = strscpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
+		if (len < 2)
 			goto err_free_inst;
 
 		if (ecb_name[len - 1] != ')')
diff --git a/crypto/xts.c b/crypto/xts.c
index c6a105dba38b9..74dc199d54867 100644
--- a/crypto/xts.c
+++ b/crypto/xts.c
@@ -395,10 +395,10 @@ static int xts_create(struct crypto_template *tmpl, struct rtattr **tb)
 	 * cipher name.
 	 */
 	if (!strncmp(cipher_name, "ecb(", 4)) {
-		unsigned len;
+		int len;
 
-		len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
-		if (len < 2 || len >= sizeof(ctx->name))
+		len = strscpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
+		if (len < 2)
 			goto err_free_inst;
 
 		if (ctx->name[len - 1] != ')')
-- 
2.40.1