diff options
| author | Alexander Lobakin | 2021-01-10 14:21:05 +0000 |
|---|---|---|
| committer | Thomas Bogendoerfer | 2021-01-13 10:59:04 +0100 |
| commit | 69e976831cd53f9ba304fd20305b2025ecc78eab (patch) | |
| tree | f7c79532e16b1f1dc788db4bc6b357aec781cb2c /arch | |
| parent | 698222457465ce343443be81c5512edda86e5914 (diff) | |
MIPS: relocatable: fix possible boot hangup with KASLR enabled
LLVM-built Linux triggered a boot hangup with KASLR enabled.
arch/mips/kernel/relocate.c:get_random_boot() uses linux_banner,
which is a string constant, as a random seed, but accesses it
as an array of unsigned long (in rotate_xor()).
When the address of linux_banner is not aligned to sizeof(long),
such access emits unaligned access exception and hangs the kernel.
Use PTR_ALIGN() to align input address to sizeof(long) and also
align down the input length to prevent possible access-beyond-end.
Fixes: 405bc8fd12f5 ("MIPS: Kernel: Implement KASLR using CONFIG_RELOCATABLE")
Cc: stable@vger.kernel.org # 4.7+
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/mips/kernel/relocate.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/relocate.c index 47aeb3350a76..0e365b7c742d 100644 --- a/arch/mips/kernel/relocate.c +++ b/arch/mips/kernel/relocate.c @@ -187,8 +187,14 @@ static int __init relocate_exception_table(long offset) static inline __init unsigned long rotate_xor(unsigned long hash, const void *area, size_t size) { - size_t i; - unsigned long *ptr = (unsigned long *)area; + const typeof(hash) *ptr = PTR_ALIGN(area, sizeof(hash)); + size_t diff, i; + + diff = (void *)ptr - area; + if (unlikely(size < diff + sizeof(hash))) + return hash; + + size = ALIGN_DOWN(size - diff, sizeof(hash)); for (i = 0; i < size / sizeof(hash); i++) { /* Rotate by odd number of bits and XOR. */ |