linux-stable.git/arch/mips/kernel/relocate.c, branch linux-4.9.y

MIPS: relocatable: fix possible boot hangup with KASLR enabled

2021-01-23T14:38:16+00:00

commit 69e976831cd53f9ba304fd20305b2025ecc78eab upstream.

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 
Tested-by: Nathan Chancellor 
Reviewed-by: Kees Cook 
Signed-off-by: Thomas Bogendoerfer 
Signed-off-by: Greg Kroah-Hartman

MIPS: KASLR: Fix handling of NULL FDT

2016-11-03T23:30:49+00:00

If platform code returns a NULL pointer to the FDT, initial_boot_params
will not get set to a valid pointer and attempting to find the /chosen
node in it will cause a NULL pointer dereference and the kernel to crash
immediately on startup - with no output to the console.

Fix this by checking that initial_boot_params is valid before using it.

Fixes: 405bc8fd12f5 ("MIPS: Kernel: Implement KASLR using CONFIG_RELOCATABLE")
Cc: stable@vger.kernel.org # 4.7+
Signed-off-by: Matt Redfearn 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14414/
Signed-off-by: Ralf Baechle

MIPS: Kernel: Implement KASLR using CONFIG_RELOCATABLE

2016-05-13T12:02:03+00:00

This patch adds KASLR to the MIPS kernel.

Entropy is derived from the banner, which will change every build and
random_get_entropy() which should provide additional runtime entropy.
Additionally the bootloader may pass entropy via the /chosen/kaslr-seed
node in device tree.

The kernel is relocated by up to RANDOMIZE_BASE_MAX_OFFSET bytes from
its link address (PHYSICAL_START). Because relocation happens so early
in the kernel boot, the amount of physical memory has not yet been
determined. This means the only way to limit relocation within the
available memory is via Kconfig.

Signed-off-by: Matt Redfearn 
Cc: linux-mips@linux-mips.org
Cc: kernel-hardening@lists.openwall.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12990/
Signed-off-by: Ralf Baechle

MIPS: Kernel: Add relocate.c

2016-05-13T12:02:02+00:00

arch/mips/kernel/relocate.c contains the functions necessary to relocate
the kernel elsewhere in memory

The kernel makes a copy of itself at the new address. It uses the
relocation table inserted by the relocs tool to fix symbol references
within the new image.

If copy/relocation is sucessful then the entry point of the new kernel
is returned, otherwise fall back to starting the kernel in place.

Signed-off-by: Matt Redfearn 
Cc: Thomas Gleixner 
Cc: James Hogan 
Cc: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: kernel-hardening@lists.openwall.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12985/
Signed-off-by: Ralf Baechle