linux-kernel - [PATCH v2] efi: fix panic in kdump kernel

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Date: Sat, 23 Mar 2024 06:33:33 +0000
From: Oleksandr Tymoshenko <ovt@...gle.com>
To: Ard Biesheuvel <ardb@...nel.org>, Johan Hovold <johan+linaro@...nel.org>
Cc: ovt@...gle.com, stable@...r.kernel.org, linux-efi@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] 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.

Fixes: bad267f9e18f ("efi: verify that variable services are supported")
Cc: stable@...r.kernel.org
Signed-off-by: Oleksandr Tymoshenko <ovt@...gle.com>
---
Changes in v2:
  - Style fix
  - Added Cc: stable
  - Added Fixes: trailer
---
 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..fdf07dd6f459 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)
+		return false;
 	status = efi.get_next_variable(&name_size, &name, &guid);
 	if (status == EFI_UNSUPPORTED)
 		return false;
-- 
2.44.0.396.g6e790dbe36-goog