diff options
| author | Ard Biesheuvel <[email protected]> | 2017-04-17 10:32:01 +0100 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2017-04-17 12:35:33 +0200 |
| commit | 197decefdb79d6f1350ba0316ce26ba737372d0c (patch) | |
| tree | 79d32c8ebc3515cf7de726694105b3aa0d203ca1 | |
| parent | e69176d68d26d63d9214797c191ce65358ea1ecf (diff) | |
efi/libstub/arm: Don't use TASK_SIZE when randomizing the RT space
As reported by James, Catalin and Mark, commit:
e69176d68d26 ("ef/libstub/arm/arm64: Randomize the base of the UEFI rt services region")
... results in a crash in the firmware, regardless of whether KASLR
is in effect or not and whether the firmware implements EFI_RNG_PROTOCOL
or not.
Mark has identified the root cause to be the inappropriate use of
TASK_SIZE in the stub, which arm64 defines as:
#define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
TASK_SIZE_32 : TASK_SIZE_64)
and testing thread flags at this point results in the dereference of
pointers in uninitialized structures.
So instead, introduce a preprocessor symbol EFI_RT_VIRTUAL_LIMIT and
define it to TASK_SIZE_64 on arm64 and TASK_SIZE on ARM, both of which
are compile time constants. Also, change the 'headroom' variable to
static const to force an error if this might change in the future.
Tested-by: Mark Rutland <[email protected]>
Tested-by: James Morse <[email protected]>
Tested-by: Catalin Marinas <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | drivers/firmware/efi/libstub/arm-stub.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c index 1e45ec51b094..8181ac179d14 100644 --- a/drivers/firmware/efi/libstub/arm-stub.c +++ b/drivers/firmware/efi/libstub/arm-stub.c @@ -32,6 +32,12 @@ #define EFI_RT_VIRTUAL_BASE SZ_512M #define EFI_RT_VIRTUAL_SIZE SZ_512M +#ifdef CONFIG_ARM64 +# define EFI_RT_VIRTUAL_LIMIT TASK_SIZE_64 +#else +# define EFI_RT_VIRTUAL_LIMIT TASK_SIZE +#endif + static u64 virtmap_base = EFI_RT_VIRTUAL_BASE; efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg, @@ -236,8 +242,9 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table, * shift of 21 bit positions into account when scaling * the headroom value using a 32-bit random value. */ - u64 headroom = TASK_SIZE - EFI_RT_VIRTUAL_BASE - - EFI_RT_VIRTUAL_SIZE; + static const u64 headroom = EFI_RT_VIRTUAL_LIMIT - + EFI_RT_VIRTUAL_BASE - + EFI_RT_VIRTUAL_SIZE; u32 rnd; status = efi_get_random_bytes(sys_table, sizeof(rnd), |