Commit be36f9e7517e ("efi: READ_ONCE rng seed size before munmap") added a READ_ONCE() and also changed the call to add_bootloader_randomness() to use the local size variable. Neither of these changes was actually needed and this was not backported to the 4.14 stable branch.
Commit 161a438d730d ("efi: random: reduce seed size to 32 bytes") reverted the addition of READ_ONCE() and added a limit to the value of size. This depends on the earlier commit, because size can now differ from seed->size, but it was wrongly backported to the 4.14 stable branch by itself.
Apply the missing change to the add_bootloader_randomness() parameter (except that here we are still using add_device_randomness()).
Fixes: 700485f70e50 ("efi: random: reduce seed size to 32 bytes") Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/firmware/efi/efi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index ed981f5e29ae..cc64869d8420 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -541,7 +541,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz, seed = early_memremap(efi.rng_seed, sizeof(*seed) + size); if (seed != NULL) { - add_device_randomness(seed->bits, seed->size); + add_device_randomness(seed->bits, size); early_memunmap(seed, sizeof(*seed) + size); pr_notice("seeding entropy pool\n"); } else {
On Thu, 2022-12-01 at 00:47 +0100, Ben Hutchings wrote:
Commit be36f9e7517e ("efi: READ_ONCE rng seed size before munmap") added a READ_ONCE() and also changed the call to add_bootloader_randomness() to use the local size variable. Neither of these changes was actually needed and this was not backported to the 4.14 stable branch.
Commit 161a438d730d ("efi: random: reduce seed size to 32 bytes") reverted the addition of READ_ONCE() and added a limit to the value of size. This depends on the earlier commit, because size can now differ from seed->size, but it was wrongly backported to the 4.14 stable branch by itself.
Apply the missing change to the add_bootloader_randomness() parameter (except that here we are still using add_device_randomness()).
[...]
This made me wonder: shouldn't commit 18b915ac6b0a ("efi/random: Treat EFI_RNG_PROTOCOL output as bootloader randomness") be applied to these older stable branches? Without that, the EFI RNG can't be distrusted if necessary.
Ben.
On Thu, Dec 01, 2022 at 12:53:03AM +0100, Ben Hutchings wrote:
On Thu, 2022-12-01 at 00:47 +0100, Ben Hutchings wrote:
Commit be36f9e7517e ("efi: READ_ONCE rng seed size before munmap") added a READ_ONCE() and also changed the call to add_bootloader_randomness() to use the local size variable. Neither of these changes was actually needed and this was not backported to the 4.14 stable branch.
Commit 161a438d730d ("efi: random: reduce seed size to 32 bytes") reverted the addition of READ_ONCE() and added a limit to the value of size. This depends on the earlier commit, because size can now differ from seed->size, but it was wrongly backported to the 4.14 stable branch by itself.
Apply the missing change to the add_bootloader_randomness() parameter (except that here we are still using add_device_randomness()).
[...]
This made me wonder: shouldn't commit 18b915ac6b0a ("efi/random: Treat EFI_RNG_PROTOCOL output as bootloader randomness") be applied to these older stable branches? Without that, the EFI RNG can't be distrusted if necessary.
Makes sense, want to send a backport on top of this one as the original will not work?
greg k-h
On Thu, Dec 01, 2022 at 12:47:22AM +0100, Ben Hutchings wrote:
Commit be36f9e7517e ("efi: READ_ONCE rng seed size before munmap") added a READ_ONCE() and also changed the call to add_bootloader_randomness() to use the local size variable. Neither of these changes was actually needed and this was not backported to the 4.14 stable branch.
Commit 161a438d730d ("efi: random: reduce seed size to 32 bytes") reverted the addition of READ_ONCE() and added a limit to the value of size. This depends on the earlier commit, because size can now differ from seed->size, but it was wrongly backported to the 4.14 stable branch by itself.
Apply the missing change to the add_bootloader_randomness() parameter (except that here we are still using add_device_randomness()).
Fixes: 700485f70e50 ("efi: random: reduce seed size to 32 bytes") Signed-off-by: Ben Hutchings ben@decadent.org.uk
drivers/firmware/efi/efi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Both now queued up, thanks,
greg k-h
linux-stable-mirror@lists.linaro.org
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Greg KH