On Mon, 2 Mar 2026 09:16:22 +0100
Jiri Olsa <[email protected]> wrote:
> Ihor and Kumar reported splat from ftrace_get_addr_curr [1], which happened
> because of the missing ftrace_lock in update_ftrace_direct_add/del functions
> allowing concurrent access to ftrace internals.
>
> The ftrace_update_ops function must be guarded by ftrace_lock, adding that.
>
> Fixes: 05dc5e9c1fe1 ("ftrace: Add update_ftrace_direct_add function")
> Fixes: 8d2c1233f371 ("ftrace: Add update_ftrace_direct_del function")
> Reported-by: Ihor Solodrai <[email protected]>
> Reported-by: Kumar Kartikeya Dwivedi <[email protected]>
> Closes:
> https://lore.kernel.org/bpf/[email protected]/
> Tested-by: Ihor Solodrai <[email protected]>
> Signed-off-by: Jiri Olsa <[email protected]>
Reviewed-by: Steven Rostedt (Google) <[email protected]>
-- Steve
> ---
> kernel/trace/ftrace.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 827fb9a0bf0d..8baf61c9be6d 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -6404,6 +6404,7 @@ int update_ftrace_direct_add(struct ftrace_ops *ops,
> struct ftrace_hash *hash)
> new_filter_hash = old_filter_hash;
> }
> } else {
> + guard(mutex)(&ftrace_lock);
> err = ftrace_update_ops(ops, new_filter_hash, EMPTY_HASH);
> /*
> * new_filter_hash is dup-ed, so we need to release it anyway,
> @@ -6530,6 +6531,7 @@ int update_ftrace_direct_del(struct ftrace_ops *ops,
> struct ftrace_hash *hash)
> ops->func_hash->filter_hash = NULL;
> }
> } else {
> + guard(mutex)(&ftrace_lock);
> err = ftrace_update_ops(ops, new_filter_hash, EMPTY_HASH);
> /*
> * new_filter_hash is dup-ed, so we need to release it anyway,
