[PATCH] module: dups: use strscpy() to copy module name in dup request

[PATCH] module: dups: use strscpy() to copy module name in dup request

[Naveen Kumar Chaudhary]

kmod_dup_request_exists_wait() uses memcpy() with strlen(module_name) to
copy into new_kmod_req->name, a fixed-size char[MODULE_NAME_LEN] buffer.
This does not bounds-check the copy and does not explicitly NUL-terminate.
The buffer is zeroed from kzalloc_obj() so NUL-termination happens to
work, but the pattern is fragile and lacks an explicit bounds check.

Replace with strscpy() which bounds the copy and guarantees
NUL-termination.

Signed-off-by: Naveen Kumar Chaudhary <naveen.osdev@gmail.com>
---
 kernel/module/dups.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/module/dups.c b/kernel/module/dups.c
index 1d720a5311ba..33bddfb57317 100644
--- a/kernel/module/dups.c
+++ b/kernel/module/dups.c
@@ -129,7 +129,7 @@ bool kmod_dup_request_exists_wait(char *module_name, bool wait, int *dup_ret)
 	if (!new_kmod_req)
 		return false;
 
-	memcpy(new_kmod_req->name, module_name, strlen(module_name));
+	strscpy(new_kmod_req->name, module_name, MODULE_NAME_LEN);
 	INIT_WORK(&new_kmod_req->complete_work, kmod_dup_request_complete);
 	INIT_DELAYED_WORK(&new_kmod_req->delete_work, kmod_dup_request_delete);
 	init_completion(&new_kmod_req->first_req_done);
-- 
2.43.0

Re: [PATCH] module: dups: use strscpy() to copy module name in dup request

[Petr Pavlu]

On 6/3/26 6:25 PM, Naveen Kumar Chaudhary wrote:
> kmod_dup_request_exists_wait() uses memcpy() with strlen(module_name) to
> copy into new_kmod_req->name, a fixed-size char[MODULE_NAME_LEN] buffer.
> This does not bounds-check the copy and does not explicitly NUL-terminate.
> The buffer is zeroed from kzalloc_obj() so NUL-termination happens to
> work, but the pattern is fragile and lacks an explicit bounds check.
> 
> Replace with strscpy() which bounds the copy and guarantees
> NUL-termination.
> 
> Signed-off-by: Naveen Kumar Chaudhary <naveen.osdev@gmail.com>
> ---
>  kernel/module/dups.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/module/dups.c b/kernel/module/dups.c
> index 1d720a5311ba..33bddfb57317 100644
> --- a/kernel/module/dups.c
> +++ b/kernel/module/dups.c
> @@ -129,7 +129,7 @@ bool kmod_dup_request_exists_wait(char *module_name, bool wait, int *dup_ret)
>  	if (!new_kmod_req)
>  		return false;
>  
> -	memcpy(new_kmod_req->name, module_name, strlen(module_name));
> +	strscpy(new_kmod_req->name, module_name, MODULE_NAME_LEN);
>  	INIT_WORK(&new_kmod_req->complete_work, kmod_dup_request_complete);
>  	INIT_DELAYED_WORK(&new_kmod_req->delete_work, kmod_dup_request_delete);
>  	init_completion(&new_kmod_req->first_req_done);

This can be shortened to:

strscpy(new_kmod_req->name, module_name);

I also suggest merging this patch and the second patch [1], which cleans
up the same issue in the module stats code, into one.

[1] https://lore.kernel.org/linux-modules/jmm7r4r3k3qt767tl7lojglosgc3umhc63cdp2fckdkgb3fzki@3fgvxgvzo5ex/

-- 
Thanks,
Petr