| Message ID | 20171023090328.6701-1-ard.biesheuvel@linaro.org |
|---|---|
| State | Accepted |
| Commit | 38fb6652229c2149e8694d57db442878fdf8a1bd |
| Headers | show |
| Series | efi/libstub: arm: don't randomize runtime regions when CONFIG_HIBERNATION=y | expand |
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c index 3061e4057483..01a9d78ee415 100644 --- a/drivers/firmware/efi/libstub/arm-stub.c +++ b/drivers/firmware/efi/libstub/arm-stub.c @@ -238,7 +238,8 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table, efi_random_get_seed(sys_table); - if (!nokaslr()) { + /* hibernation expects the runtime regions to stay in the same place */ + if (!IS_ENABLED(CONFIG_HIBERNATION) && !nokaslr()) { /* * Randomize the base of the UEFI runtime services region. * Preserve the 2 MB alignment of the region by taking a
Commit e69176d68d26 ef/libstub/arm/arm64: Randomize the base of the UEFI rt services region implemented randomization of the virtual mapping that the OS chooses for the UEFI runtime services. This was motivated by the fact that UEFI usually does not bother to specify any permission restrictions for those regions, making them prime real estate for exploitation now that the OS is getting more and more careful not to leave any R+W+X mapped regions lying around. However, this randomization breaks assumptions in the resume from hibernation code, which expects all memory regions populated by UEFI to remain in the same place, including their virtual mapping into the OS memory space. While this assumption may not be entirely reasonable in the first place, breaking it deliberately does not make a lot of sense either. So let's refrain from this randomization pass if CONFIG_HIBERNATION=y. Cc: James Morse <james.morse@arm.com> Cc: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- drivers/firmware/efi/libstub/arm-stub.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html