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authorMark Rutland <mark.rutland@arm.com>2016-06-13 11:15:14 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-07-27 08:42:16 -0700
commite75da3fe88133b6e6822f9098aabb893e98a799e (patch)
tree1a83947eca908a82d92c667fb439d4929d45798c /net/unix/af_unix.c
parent896f190d1b7a02f78bd7893e4fd8265f37ae619d (diff)
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>
Diffstat (limited to 'net/unix/af_unix.c')
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