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Mark Rutland 4310b6bfa8 arm64: fix dump_instr when PAN and UAO are in use

commit c5cea06be060f38e5400d796e61cfc8c36e52924 upstream.

If the kernel is set to show unhandled signals, and a user task does not
handle a SIGILL as a result of an instruction abort, we will attempt to
log the offending instruction with dump_instr before killing the task.

We use dump_instr to log the encoding of the offending userspace
instruction. However, dump_instr is also used to dump instructions from
kernel space, and internally always switches to KERNEL_DS before dumping
the instruction with get_user. When both PAN and UAO are in use, reading
a user instruction via get_user while in KERNEL_DS will result in a
permission fault, which leads to an Oops.

As we have regs corresponding to the context of the original instruction
abort, we can inspect this and only flip to KERNEL_DS if the original
abort was taken from the kernel, avoiding this issue. At the same time,
remove the redundant (and incorrect) comments regarding the order
dump_mem and dump_instr are called in.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>
Fixes: 57f4959bad0a154a ("arm64: kernel: Add support for User Access Override")
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2017-11-24 08:32:25 +01:00

alpha

alpha: uapi: Add support for __SANE_USERSPACE_TYPES__

2017-09-07 08:34:09 +02:00

arc

ARC: Re-enable MMU upon Machine Check exception

2017-09-27 11:00:16 +02:00

arm

ARM: OMAP2+: Fix init for multiple quirks for the same SoC

2017-11-21 09:21:19 +01:00

arm64

arm64: fix dump_instr when PAN and UAO are in use