The following commit has been merged into the efi/urgent branch of tip: Commit-ID: be36f9e7517e17810ec369626a128d7948942259 Gitweb: https://git.kernel.org/tip/be36f9e7517e17810ec369626a128d7948942259 Author: Jason A. Donenfeld <Jason@xxxxxxxxx> AuthorDate: Fri, 21 Feb 2020 09:48:49 +01:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Wed, 26 Feb 2020 15:31:43 +01:00 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: 636259880a7e ("efi: Add support for seeding the RNG from a UEFI ...") Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Cc: linux-efi@xxxxxxxxxxxxxxx Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20200217123354.21140-1-Jason@xxxxxxxxx Link: https://lore.kernel.org/r/20200221084849.26878-5-ardb@xxxxxxxxxx --- 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 621220a..21ea99f 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");
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