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Date: Mon, 17 Feb 2020 13:33:54 +0100 From: "Jason A. Donenfeld" <Jason@...c4.com> To: ardb@...nel.org, linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org Cc: "Jason A. Donenfeld" <Jason@...c4.com>, stable@...r.kernel.org Subject: [PATCH] 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. Signed-off-by: Jason A. Donenfeld <Jason@...c4.com> Cc: Ard Biesheuvel <ardb@...nel.org> Cc: stable@...r.kernel.org --- drivers/firmware/efi/efi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 621220ab3d0e..21ea99f65113 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -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"); -- 2.25.0
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