2024-03-22 01:09:05

by Oleksandr Tymoshenko

Subject: [PATCH] efi: fix panic in kdump kernel

Check if get_next_variable() is actually valid pointer before
calling it. In kdump kernel this method is set to NULL that causes
panic during the kexec-ed kernel boot.

Tested with QEMU and OVMF firmware.

Signed-off-by: Oleksandr Tymoshenko <[email protected]>
---
drivers/firmware/efi/efi.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 8859fb0b006d..800b85807a02 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -203,6 +203,8 @@ static bool generic_ops_supported(void)

name_size = sizeof(name);

+ if (efi.get_next_variable == NULL)
+ return false;
status = efi.get_next_variable(&name_size, &name, &guid);
if (status == EFI_UNSUPPORTED)
return false;
--
2.44.0.396.g6e790dbe36-goog

2024-03-22 08:00:21

by Johan Hovold

Subject: Re: [PATCH] efi: fix panic in kdump kernel

On Fri, Mar 22, 2024 at 01:08:45AM +0000, Oleksandr Tymoshenko wrote:
> Check if get_next_variable() is actually valid pointer before
> calling it. In kdump kernel this method is set to NULL that causes
> panic during the kexec-ed kernel boot.
>
> Tested with QEMU and OVMF firmware.

Sounds like you want a Fixes and CC stable tag here as well.

> Signed-off-by: Oleksandr Tymoshenko <[email protected]>
> ---
> drivers/firmware/efi/efi.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 8859fb0b006d..800b85807a02 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -203,6 +203,8 @@ static bool generic_ops_supported(void)
>
> name_size = sizeof(name);
>
> + if (efi.get_next_variable == NULL)
> + return false;

Please move this check above the name_size initialisation and make sure
you have a new line before and after.

I'd also suggest rewriting this as:

if (!efi.get_next_variable)
return false;

> status = efi.get_next_variable(&name_size, &name, &guid);
> if (status == EFI_UNSUPPORTED)
> return false;

Johan