On 9/9/25 4:22 AM, Sudhakar Kuppusamy wrote:
On 9 Sep 2025, at 12:25 PM, Srish Srinivasan <[email protected]> wrote:
Many modules call grub_unregister_{command(), extcmd()} from
GRUB_MOD_FINI() without checking for a failure in registration.
This could lead to a NULL pointer dereference in unregistration.
Perform explicit NULL check in both the unregister helpers.
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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