[PATCH] ftrace: Make ftrace_graph_ent depth field signed

[PATCH] ftrace: Make ftrace_graph_ent depth field signed

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

The code has integrity checks to make sure that depth never goes below
zero. But the depth field has recently been converted to unsigned long
from "int" (for alignment reasons). As unsigned long can never be less
than zero, the integrity checks no longer work.

Convert depth to long from unsigned long to allow the integrity checks to
work again.

Cc: stable@vger.kernel.org
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/aS6kGi0maWBl-MjZ@stanley.mountain/
Fixes: f83ac7544fbf7 ("function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/linux/ftrace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 770f0dc993cc..a3a8989e3268 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1167,7 +1167,7 @@ static inline void ftrace_init(void) { }
  */
 struct ftrace_graph_ent {
 	unsigned long func; /* Current function */
-	unsigned long depth;
+	long depth; /* signed to check for less than zero */
 } __packed;
 
 /*
-- 
2.51.0

Re: [PATCH] ftrace: Make ftrace_graph_ent depth field signed

[Masami Hiramatsu]

On Fri, 2 Jan 2026 14:31:48 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: Steven Rostedt <rostedt@goodmis.org>
> 
> The code has integrity checks to make sure that depth never goes below
> zero. But the depth field has recently been converted to unsigned long
> from "int" (for alignment reasons). As unsigned long can never be less
> than zero, the integrity checks no longer work.
> 
> Convert depth to long from unsigned long to allow the integrity checks to
> work again.
> 
> Cc: stable@vger.kernel.org
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/all/aS6kGi0maWBl-MjZ@stanley.mountain/
> Fixes: f83ac7544fbf7 ("function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously")
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thanks,

> ---
>  include/linux/ftrace.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index 770f0dc993cc..a3a8989e3268 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -1167,7 +1167,7 @@ static inline void ftrace_init(void) { }
>   */
>  struct ftrace_graph_ent {
>  	unsigned long func; /* Current function */
> -	unsigned long depth;
> +	long depth; /* signed to check for less than zero */
>  } __packed;
>  
>  /*
> -- 
> 2.51.0
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>