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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2017-10-25 11:04:48 +0100
committerIngo Molnar <mingo@kernel.org>2017-10-25 12:10:59 +0200
commit38fb6652229c2149e8694d57db442878fdf8a1bd (patch)
treeaa204ba3d73d95c8a73c61b48ece04163887c4c1
parent092e72c9edab16d4d6ad10c683a95047d53b6db4 (diff)
downloadlinux-stericsson-38fb6652229c2149e8694d57db442878fdf8a1bd.tar.gz
efi/libstub/arm: Don't randomize runtime regions when CONFIG_HIBERNATION=y
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. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: James Morse <james.morse@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20171025100448.26056-3-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--drivers/firmware/efi/libstub/arm-stub.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index 1cb2d1c070c3..a94601d5939e 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