Commit 69cbeb61 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Revert "efi: random: refresh non-volatile random seed when RNG is initialized" 



This reverts commit e7b813b3 (and the
subsequent fix for it: 41a15855 "efi: random: fix NULL-deref when
refreshing seed").

It turns otu to cause non-deterministic boot stalls on at least a HP
6730b laptop.

Reported-and-bisected-by: default avatarSami Korkalainen <sami.korkalainen@proton.me>
Link: https://lore.kernel.org/all/GQUnKz2al3yke5mB2i1kp3SzNHjK8vi6KJEh7rnLrOQ24OrlljeCyeWveLW9pICEmB9Qc8PKdNt3w1t_g3-Uvxq1l8Wj67PpoMeWDoH8PKk=@proton.me/


Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: stable@kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2214170c

drivers/firmware/efi/efi.c

+0 −21
Original line number Diff line number Diff line
@@ -361,24 +361,6 @@ static void __init efi_debugfs_init(void) 
static inline void efi_debugfs_init(void) {}

#endif



static void refresh_nv_rng_seed(struct work_struct *work)

{

	u8 seed[EFI_RANDOM_SEED_SIZE];



	get_random_bytes(seed, sizeof(seed));

	efi.set_variable(L"RandomSeed", &LINUX_EFI_RANDOM_SEED_TABLE_GUID,

			 EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS |

			 EFI_VARIABLE_RUNTIME_ACCESS, sizeof(seed), seed);

	memzero_explicit(seed, sizeof(seed));

}

static int refresh_nv_rng_seed_notification(struct notifier_block *nb, unsigned long action, void *data)

{

	static DECLARE_WORK(work, refresh_nv_rng_seed);

	schedule_work(&work);

	return NOTIFY_DONE;

}

static struct notifier_block refresh_nv_rng_seed_nb = { .notifier_call = refresh_nv_rng_seed_notification };



/*

 * We register the efi subsystem with the firmware subsystem and the

 * efivars subsystem with the efi subsystem, if the system was booted with
@@ -451,9 +433,6 @@ static int __init efisubsys_init(void) 
		platform_device_register_simple("efi_secret", 0, NULL, 0);

#endif



	if (efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))

		execute_with_initialized_rng(&refresh_nv_rng_seed_nb);



	return 0;



err_remove_group: