From 41a15855c1ee390a0ae9d0c29d32b451dd30a600 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Fri, 16 Dec 2022 10:15:14 +0100 Subject: efi: random: fix NULL-deref when refreshing seed Do not try to refresh the RNG seed in case the firmware does not support setting variables. This is specifically needed to prevent a NULL-pointer dereference on the Lenovo X13s with some firmware revisions, or more generally, whenever the runtime services have been disabled (e.g. efi=noruntime or with PREEMPT_RT). Fixes: e7b813b32a42 ("efi: random: refresh non-volatile random seed when RNG is initialized") Reported-by: Steev Klimaszewski Reported-by: Bjorn Andersson Tested-by: Steev Klimaszewski Tested-by: Andrew Halaney # sc8280xp-lenovo-thinkpad-x13s Signed-off-by: Johan Hovold Signed-off-by: Jason A. Donenfeld --- drivers/firmware/efi/efi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/firmware') diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 31a4090c66b3..09716eebe8ac 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -429,7 +429,9 @@ static int __init efisubsys_init(void) platform_device_register_simple("efi_secret", 0, NULL, 0); #endif - execute_with_initialized_rng(&refresh_nv_rng_seed_nb); + if (efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE)) + execute_with_initialized_rng(&refresh_nv_rng_seed_nb); + return 0; err_remove_group: -- cgit v1.2.3