efi: READ_ONCE rng seed size before munmap

commit be36f9e7517e17810ec369626a128d7948942259 upstream.

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: 636259880a ("efi: Add support for seeding the RNG from a UEFI ...")
Signed-off-by: Jason A. Donenfeld <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: [email protected]
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
This commit is contained in:
Jason A. Donenfeld 2020-02-21 09:48:49 +01:00 • committed by Greg Kroah-Hartman
commit e657b1f6b9

View file

@ -544,7 +544,7 @@ 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");
@ -554,7 +554,7 @@ 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");