Messages in this thread Patch in this message | | | From | Johan Hovold <> | Subject | [PATCH v2] efi: random: fix NULL-deref when refreshing seed | Date | Mon, 19 Dec 2022 11:12:37 +0100 |
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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 <steev@kali.org> Reported-by: Bjorn Andersson <andersson@kernel.org> Tested-by: Andrew Halaney <ahalaney@redhat.com> # sc8280xp-lenovo-thinkpad-x13s Signed-off-by: Johan Hovold <johan+linaro@kernel.org> ---
Changes in v2 - amend commit message with a comment on this being needed whenever the runtime services have been disabled
drivers/firmware/efi/efi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
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: -- 2.37.4
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