Looks good to me, thank you.

Reviewed-by: Andrew Hamilton <[email protected]>

On Mon, Sep 22, 2025 at 1:04 AM Srish Srinivasan <[email protected]> wrote:
>
> During command registration, grub_register_command_prio
> returns a 0 when there is a failure in memory allocation.
> In such a situation, calls to grub_unregister_{command(),
> extcmd()} during command unregistration will result in
> dereferencing a NULL pointer.
>
> Perform explicit NULL check in both the unregister helpers to
> prevent undefined behaviour due to a NULL pointer dereference.
>
> Signed-off-by: Srish Srinivasan <[email protected]>
> Reviewed-by: Sudhakar Kuppusamy <[email protected]>
> Reviewed-by: Stefan Berger <[email protected]>
> ---
>  grub-core/commands/extcmd.c | 3 +++
>  grub-core/kern/command.c    | 3 +++
>  2 files changed, 6 insertions(+)
>
> diff --git a/grub-core/commands/extcmd.c b/grub-core/commands/extcmd.c
> index c236be13a..7f8cb3f67 100644
> --- a/grub-core/commands/extcmd.c
> +++ b/grub-core/commands/extcmd.c
> @@ -139,6 +139,9 @@ grub_register_extcmd_lockdown (const char *name, 
> grub_extcmd_func_t func,
>  void
>  grub_unregister_extcmd (grub_extcmd_t ext)
>  {
> +  if (ext == NULL)
> +    return;
> +
>    grub_unregister_command (ext->cmd);
>    grub_free (ext);
>  }
> diff --git a/grub-core/kern/command.c b/grub-core/kern/command.c
> index 5812e131c..a1b4c81a9 100644
> --- a/grub-core/kern/command.c
> +++ b/grub-core/kern/command.c
> @@ -104,6 +104,9 @@ grub_register_command_lockdown (const char *name,
>  void
>  grub_unregister_command (grub_command_t cmd)
>  {
> +  if (cmd == NULL)
> +    return;
> +
>    if ((cmd->prio & GRUB_COMMAND_FLAG_ACTIVE) && (cmd->next))
>      cmd->next->prio |= GRUB_COMMAND_FLAG_ACTIVE;
>    grub_list_remove (GRUB_AS_LIST (cmd));
> --
> 2.51.0
>
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