On 2018-04-22 21:06, Mark Rutland wrote: > On Sun, Apr 22, 2018 at 12:47:57PM +0200, Jan Kiszka wrote: >> Hi, >> >> this can be triggered simply by running >> >> # echo 0 > /sys/devices/system/cpu/cpu3/online >> # echo 1 > /sys/devices/system/cpu/cpu3/online >> >> [ 455.904854] >> ================================================================== >> [ 455.906108] BUG: KASAN: global-out-of-bounds in >> unmap_kernel_at_el0+0x70/0x1a0 >> [ 455.906668] Read of size 4 at addr ffff200008e3a9d8 by task swapper/3/0 > > It looks like we miss a sentinel in kpti_safe_list. > > Does the below help? > > Mark. > > ---->8---- > From ade322407e3d6d1f50e558ebd50d2c1c7bd811c2 Mon Sep 17 00:00:00 2001 > From: Mark Rutland <mark.rutl...@arm.com> > Date: Sun, 22 Apr 2018 19:58:08 +0100 > Subject: [PATCH] arm64: add sentinel to kpti_safe_list > > We're missing a sentinel entry in kpti_safe_list. Thus is_midr_in_range_list() > can walk past the end of kpti_safe_list. Depending on the contents of memory, > this could erroneously match a CPU's MIDR, cause a data abort, or other bad > outcomes. > > Add the sentinel entry to avoid this. > > Fixes: be5b299830c63ed7 ("arm64: capabilities: Add support for checks based > on a list of MIDRs") > Signed-off-by: Mark Rutland <mark.rutl...@arm.com> > Reported-by: Jan Kiszka <jan.kis...@web.de> > Cc: Catalin Marinas <catalin.mari...@arm.com> > Cc: Suzuki K Poulose <suzuki.poul...@arm.com> > Cc: Will Deacon <will.dea...@arm.com> > --- > arch/arm64/kernel/cpufeature.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 536d572e5596..9d1b06d67c53 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -868,6 +868,7 @@ static bool unmap_kernel_at_el0(const struct > arm64_cpu_capabilities *entry, > static const struct midr_range kpti_safe_list[] = { > MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2), > MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN), > + { /* sentinel */ } > }; > char const *str = "command line option"; > >
Jep, all fine now! Jan
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