Commit be36f9e7 authored Feb 21, 2020 by Jason A. Donenfeld Committed by Ingo Molnar Feb 26, 2020

efi: READ_ONCE rng seed size before munmap



This function is consistent with using size instead of seed->size
(except for one place that this patch fixes), but it reads seed->size
without using READ_ONCE, which means the compiler might still do
something unwanted. So, this commit simply adds the READ_ONCE
wrapper.

Fixes: 63625988 ("efi: Add support for seeding the RNG from a UEFI ...")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-efi@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200217123354.21140-1-Jason@zx2c4.com
Link: https://lore.kernel.org/r/20200221084849.26878-5-ardb@kernel.org

parent 8319e9d5

drivers/firmware/efi/efi.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -552,7 +552,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,

		seed = early_memremap(efi.rng_seed, sizeof(*seed));
		if (seed != NULL) {
		size = seed->size;
		size = READ_ONCE(seed->size);
		early_memunmap(seed, sizeof(*seed));
		} else {
		pr_err("Could not map UEFI random seed!\n");
		@@ -562,7 +562,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
		sizeof(*seed) + size);
		if (seed != NULL) {
		pr_notice("seeding entropy pool\n");
		add_bootloader_randomness(seed->bits, seed->size);
		add_bootloader_randomness(seed->bits, size);
		early_memunmap(seed, sizeof(*seed) + size);
		} else {
		pr_err("Could not map UEFI random seed!\n");

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