From fa93f2412b260572675bd4b4dacb6a73d2b42471 Mon Sep 17 00:00:00 2001 From: Srish Srinivasan Date: Mon, 22 Sep 2025 11:32:46 +0530 Subject: [PATCH] kern/command,commands/extcmd: Perform explicit NULL check in both the unregister helpers 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 unregister helpers to prevent undefined behaviour due to a NULL pointer dereference. Signed-off-by: Srish Srinivasan Reviewed-by: Sudhakar Kuppusamy Reviewed-by: Stefan Berger Reviewed-by: Daniel Kiper --- 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));