trace/events/task.h: Replace strlcpy with strscpy

[PATCH] trace/events/task.h: Replace strlcpy with strscpy

Posted by Azeem Shaikh 2 years, 5 months ago

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>
---
 include/trace/events/task.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/trace/events/task.h b/include/trace/events/task.h
index 64d160930b0d..47b527464d1a 100644
--- a/include/trace/events/task.h
+++ b/include/trace/events/task.h
@@ -47,7 +47,7 @@ TRACE_EVENT(task_rename,
 	TP_fast_assign(
 		__entry->pid = task->pid;
 		memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN);
-		strlcpy(entry->newcomm, comm, TASK_COMM_LEN);
+		strscpy(entry->newcomm, comm, TASK_COMM_LEN);
 		__entry->oom_score_adj = task->signal->oom_score_adj;
 	),

--
2.42.0.283.g2d96d420d3-goog

Re: [PATCH] trace/events/task.h: Replace strlcpy with strscpy

Posted by Justin Stitt 2 years, 5 months ago

On Thu, Aug 31, 2023 at 12:42 PM Azeem Shaikh <azeemshaikh38@gmail.com> 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: Justin Stitt <justinstitt@google.com>

> ---
>  include/trace/events/task.h |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/trace/events/task.h b/include/trace/events/task.h
> index 64d160930b0d..47b527464d1a 100644
> --- a/include/trace/events/task.h
> +++ b/include/trace/events/task.h
> @@ -47,7 +47,7 @@ TRACE_EVENT(task_rename,
>         TP_fast_assign(
>                 __entry->pid = task->pid;
>                 memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN);
> -               strlcpy(entry->newcomm, comm, TASK_COMM_LEN);
> +               strscpy(entry->newcomm, comm, TASK_COMM_LEN);
>                 __entry->oom_score_adj = task->signal->oom_score_adj;
>         ),
>
> --
> 2.42.0.283.g2d96d420d3-goog
>
>

Re: [PATCH] trace/events/task.h: Replace strlcpy with strscpy

Posted by Kees Cook 2 years, 5 months ago

On Thu, Aug 31, 2023 at 07:42:12PM +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