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authorJohan Hovold <johan+linaro@kernel.org>2022-12-16 12:15:14 +0300
committerJason A. Donenfeld <Jason@zx2c4.com>2022-12-20 05:13:45 +0300
commit41a15855c1ee390a0ae9d0c29d32b451dd30a600 (patch)
treed3e2b4f0e9024d7b9d385782e18bcdaedbf1069b
parent6bb20c152b6bf7dd8ffb248f33c2593fd9aeb318 (diff)
downloadlinux-41a15855c1ee390a0ae9d0c29d32b451dd30a600.tar.xz
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 <steev@kali.org> Reported-by: Bjorn Andersson <andersson@kernel.org> Tested-by: Steev Klimaszewski <steev@kali.org> Tested-by: Andrew Halaney <ahalaney@redhat.com> # sc8280xp-lenovo-thinkpad-x13s Signed-off-by: Johan Hovold <johan+linaro@kernel.org> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
-rw-r--r--drivers/firmware/efi/efi.c4
1 files changed, 3 insertions, 1 deletions
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: