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kern/command,commands/extcmd: Perform explicit NULL check in both the unregister helpers

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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 <ssrish@linux.ibm.com>
Reviewed-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Srish Srinivasan 2025-09-22 11:32:46 +05:30 committed by Daniel Kiper
parent 9a725391f1
commit fa93f2412b
2 changed files with 6 additions and 0 deletions
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3
grub-core/commands/extcmd.c
View File

@ -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);
}

3
grub-core/kern/command.c
View File

@ -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));