diff options
| author | Russell King <rmk+kernel@armlinux.org.uk> | 2018-05-14 09:40:24 +0100 |
|---|---|---|
| committer | Tao Huang <huangtao@rock-chips.com> | 2018-12-12 11:05:36 +0800 |
| commit | b5eac72e73dc12c2ebdfde009ff8e7f8540e9eb9 (patch) | |
| tree | 6d7939924eceb0ab2050ee44fe2361a1be57035f /arch/arm/include | |
| parent | 042dc8706f8005c5ebb3f0d0eaee99fb722fb9c3 (diff) | |
UPSTREAM: ARM: spectre-v1: mitigate user accesses
Spectre variant 1 attacks are about this sequence of pseudo-code:
index = load(user-manipulated pointer);
access(base + index * stride);
In order for the cache side-channel to work, the access() must me made
to memory which userspace can detect whether cache lines have been
loaded. On 32-bit ARM, this must be either user accessible memory, or
a kernel mapping of that same user accessible memory.
The problem occurs when the load() speculatively loads privileged data,
and the subsequent access() is made to user accessible memory.
Any load() which makes use of a user-maniplated pointer is a potential
problem if the data it has loaded is used in a subsequent access. This
also applies for the access() if the data loaded by that access is used
by a subsequent access.
Harden the get_user() accessors against Spectre attacks by forcing out
of bounds addresses to a NULL pointer. This prevents get_user() being
used as the load() step above. As a side effect, put_user() will also
be affected even though it isn't implicated.
Also harden copy_from_user() by redoing the bounds check within the
arm_copy_from_user() code, and NULLing the pointer if out of bounds.
Change-Id: I7598d2a637267b5979a7013cf450a80caaa2044f
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Tao Huang <huangtao@rock-chips.com>
(cherry picked from commit a3c0f84765bb429ba0fd23de1c57b5e1591c9389)
Diffstat (limited to 'arch/arm/include')
| -rw-r--r-- | arch/arm/include/asm/assembler.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index 307901f88a1e..483481c6937e 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -454,6 +454,10 @@ THUMB( orr \reg , \reg , #PSR_T_BIT ) adds \tmp, \addr, #\size - 1 sbcccs \tmp, \tmp, \limit bcs \bad +#ifdef CONFIG_CPU_SPECTRE + movcs \addr, #0 + csdb +#endif #endif .endm |