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().
No return values were used, so direct replacement is safe.

[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>
---
 drivers/most/configfs.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/most/configfs.c b/drivers/most/configfs.c
index 27b0c923597f..36d8c917f65f 100644
--- a/drivers/most/configfs.c
+++ b/drivers/most/configfs.c
@@ -204,7 +204,7 @@ static ssize_t mdev_link_device_store(struct config_item *item,
 {
 	struct mdev_link *mdev_link = to_mdev_link(item);
 
-	strlcpy(mdev_link->device, page, sizeof(mdev_link->device));
+	strscpy(mdev_link->device, page, sizeof(mdev_link->device));
 	strim(mdev_link->device);
 	return count;
 }
@@ -219,7 +219,7 @@ static ssize_t mdev_link_channel_store(struct config_item *item,
 {
 	struct mdev_link *mdev_link = to_mdev_link(item);
 
-	strlcpy(mdev_link->channel, page, sizeof(mdev_link->channel));
+	strscpy(mdev_link->channel, page, sizeof(mdev_link->channel));
 	strim(mdev_link->channel);
 	return count;
 }
@@ -234,7 +234,7 @@ static ssize_t mdev_link_comp_store(struct config_item *item,
 {
 	struct mdev_link *mdev_link = to_mdev_link(item);
 
-	strlcpy(mdev_link->comp, page, sizeof(mdev_link->comp));
+	strscpy(mdev_link->comp, page, sizeof(mdev_link->comp));
 	strim(mdev_link->comp);
 	return count;
 }
@@ -250,7 +250,7 @@ static ssize_t mdev_link_comp_params_store(struct config_item *item,
 {
 	struct mdev_link *mdev_link = to_mdev_link(item);
 
-	strlcpy(mdev_link->comp_params, page, sizeof(mdev_link->comp_params));
+	strscpy(mdev_link->comp_params, page, sizeof(mdev_link->comp_params));
 	strim(mdev_link->comp_params);
 	return count;
 }

On Tue, 23 May 2023 02:16:40 +0000, Azeem Shaikh wrote:
> 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().
> No return values were used, so direct replacement is safe.
> 
> [...]

Applied to for-next/hardening, thanks!

[1/1] staging: most: Replace all non-returning strlcpy with strscpy
      https://git.kernel.org/kees/c/32c7fb186c1b

-- 
Kees Cook

On Tue, May 23, 2023 at 02:16:40AM +0000, Azeem Shaikh wrote:
> 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().
> No return values were used, so direct replacement is safe.
> 
> [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>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook