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* [PATCH] kern: perform NULL check in unregister paths (command/extcmd)
@ 2025-09-08 18:10 Srish Srinivasan
  2025-09-09  5:01 ` Sudhakar Kuppusamy
  0 siblings, 1 reply; 3+ messages in thread
From: Srish Srinivasan @ 2025-09-08 18:10 UTC (permalink / raw)
  To: grub-devel
  Cc: daniel.kiper, phcoder, sudhakar, stefanb, nayna, sridharm, ssrish

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 <ssrish@linux.ibm.com>
---
 grub-core/commands/extcmd.c | 2 ++
 grub-core/kern/command.c    | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/grub-core/commands/extcmd.c b/grub-core/commands/extcmd.c
index c236be13a..f142305ed 100644
--- a/grub-core/commands/extcmd.c
+++ b/grub-core/commands/extcmd.c
@@ -139,6 +139,8 @@ grub_register_extcmd_lockdown (const char *name, grub_extcmd_func_t func,
 void
 grub_unregister_extcmd (grub_extcmd_t ext)
 {
+  if (!ext)
+    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..3ab93ce20 100644
--- a/grub-core/kern/command.c
+++ b/grub-core/kern/command.c
@@ -104,6 +104,8 @@ grub_register_command_lockdown (const char *name,
 void
 grub_unregister_command (grub_command_t cmd)
 {
+  if (!cmd)
+    return;
   if ((cmd->prio & GRUB_COMMAND_FLAG_ACTIVE) && (cmd->next))
     cmd->next->prio |= GRUB_COMMAND_FLAG_ACTIVE;
   grub_list_remove (GRUB_AS_LIST (cmd));
-- 
2.48.1


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Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel

^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] kern: perform NULL check in unregister paths (command/extcmd)
  2025-09-08 18:10 [PATCH] kern: perform NULL check in unregister paths (command/extcmd) Srish Srinivasan
@ 2025-09-09  5:01 ` Sudhakar Kuppusamy
  2025-09-09  6:51   ` Srish Srinivasan
  0 siblings, 1 reply; 3+ messages in thread
From: Sudhakar Kuppusamy @ 2025-09-09  5:01 UTC (permalink / raw)
  To: Srish Srinivasan
  Cc: grub-devel, daniel.kiper, phcoder, stefanb, nayna, sridharm



> On 8 Sep 2025, at 11:40 PM, Srish Srinivasan <ssrish@linux.ibm.com> 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 <ssrish@linux.ibm.com>
> ---
> grub-core/commands/extcmd.c | 2 ++
> grub-core/kern/command.c    | 2 ++
> 2 files changed, 4 insertions(+)
> 
> diff --git a/grub-core/commands/extcmd.c b/grub-core/commands/extcmd.c
> index c236be13a..f142305ed 100644
> --- a/grub-core/commands/extcmd.c
> +++ b/grub-core/commands/extcmd.c
> @@ -139,6 +139,8 @@ grub_register_extcmd_lockdown (const char *name, grub_extcmd_func_t func,
> void
> grub_unregister_extcmd (grub_extcmd_t ext)
> {
> +  if (!ext)
For pointer, use ext == NULL
> +    return;

It would be nice if add empty line here
>   grub_unregister_command (ext->cmd);
>   grub_free (ext);
> }
> diff --git a/grub-core/kern/command.c b/grub-core/kern/command.c
> index 5812e131c..3ab93ce20 100644
> --- a/grub-core/kern/command.c
> +++ b/grub-core/kern/command.c
> @@ -104,6 +104,8 @@ grub_register_command_lockdown (const char *name,
> void
> grub_unregister_command (grub_command_t cmd)
> {
> +  if (!cmd)
For pointer, use cmd == NULL
> +    return;
It would be nice if add empty line here

Thanks,
Sudhakar
>   if ((cmd->prio & GRUB_COMMAND_FLAG_ACTIVE) && (cmd->next))
>     cmd->next->prio |= GRUB_COMMAND_FLAG_ACTIVE;
>   grub_list_remove (GRUB_AS_LIST (cmd));
> -- 
> 2.48.1
> 


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Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH] kern: perform NULL check in unregister paths (command/extcmd)
  2025-09-09  5:01 ` Sudhakar Kuppusamy
@ 2025-09-09  6:51   ` Srish Srinivasan
  0 siblings, 0 replies; 3+ messages in thread
From: Srish Srinivasan @ 2025-09-09  6:51 UTC (permalink / raw)
  To: The development of GNU GRUB, Sudhakar Kuppusamy
  Cc: daniel.kiper, phcoder, stefanb, nayna, sridharm


On 9/9/25 10:31 AM, Sudhakar Kuppusamy wrote:
>
>> On 8 Sep 2025, at 11:40 PM, Srish Srinivasan <ssrish@linux.ibm.com> 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 <ssrish@linux.ibm.com>
>> ---
>> grub-core/commands/extcmd.c | 2 ++
>> grub-core/kern/command.c    | 2 ++
>> 2 files changed, 4 insertions(+)
>>
>> diff --git a/grub-core/commands/extcmd.c b/grub-core/commands/extcmd.c
>> index c236be13a..f142305ed 100644
>> --- a/grub-core/commands/extcmd.c
>> +++ b/grub-core/commands/extcmd.c
>> @@ -139,6 +139,8 @@ grub_register_extcmd_lockdown (const char *name, grub_extcmd_func_t func,
>> void
>> grub_unregister_extcmd (grub_extcmd_t ext)
>> {
>> +  if (!ext)
> For pointer, use ext == NULL
>> +    return;
> It would be nice if add empty line here
>>    grub_unregister_command (ext->cmd);
>>    grub_free (ext);
>> }
>> diff --git a/grub-core/kern/command.c b/grub-core/kern/command.c
>> index 5812e131c..3ab93ce20 100644
>> --- a/grub-core/kern/command.c
>> +++ b/grub-core/kern/command.c
>> @@ -104,6 +104,8 @@ grub_register_command_lockdown (const char *name,
>> void
>> grub_unregister_command (grub_command_t cmd)
>> {
>> +  if (!cmd)
> For pointer, use cmd == NULL
>> +    return;
> It would be nice if add empty line here
>
> Thanks,
> Sudhakar
Hi Sudhakar,
Thanks for the review.

Will send out v2 with the fixes.
>>    if ((cmd->prio & GRUB_COMMAND_FLAG_ACTIVE) && (cmd->next))
>>      cmd->next->prio |= GRUB_COMMAND_FLAG_ACTIVE;
>>    grub_list_remove (GRUB_AS_LIST (cmd));
>> -- 
>> 2.48.1
>>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel

_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2025-09-09  6:52 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2025-09-08 18:10 [PATCH] kern: perform NULL check in unregister paths (command/extcmd) Srish Srinivasan
2025-09-09  5:01 ` Sudhakar Kuppusamy
2025-09-09  6:51   ` Srish Srinivasan

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