Patch "MIPS: kprobes: flush_insn_slot should flush only if probe initialised" has been added to the 4.9-stable tree

Patch "MIPS: kprobes: flush_insn_slot should flush only if probe initialised" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    MIPS: kprobes: flush_insn_slot should flush only if probe initialised

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mips-kprobes-flush_insn_slot-should-flush-only-if-probe-initialised.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Apr  9 17:09:24 CEST 2018
From: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Date: Thu, 8 Jun 2017 15:20:32 +0200
Subject: MIPS: kprobes: flush_insn_slot should flush only if probe initialised

From: Marcin Nowakowski <marcin.nowakowski@imgtec.com>


[ Upstream commit 698b851073ddf5a894910d63ca04605e0473414e ]

When ftrace is used with kprobes, it is possible for a kprobe to contain
an invalid location (ie. only initialised to 0 and not to a specific
location in the code). Trying to perform a cache flush on such location
leads to a crash r4k_flush_icache_range().

Fixes: c1bf207d6ee1 ("MIPS: kprobe: Add support.")
Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16296/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/include/asm/kprobes.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/mips/include/asm/kprobes.h
+++ b/arch/mips/include/asm/kprobes.h
@@ -40,7 +40,8 @@ typedef union mips_instruction kprobe_op
 
 #define flush_insn_slot(p)						\
 do {									\
-	flush_icache_range((unsigned long)p->addr,			\
+	if (p->addr)							\
+		flush_icache_range((unsigned long)p->addr,		\
 			   (unsigned long)p->addr +			\
 			   (MAX_INSN_SIZE * sizeof(kprobe_opcode_t)));	\
 } while (0)


Patches currently in stable-queue which might be from marcin.nowakowski@imgtec.com are

queue-4.9/mips-mm-fixed-mappings-correct-initialisation.patch
queue-4.9/mips-mm-adjust-pkmap-location.patch
queue-4.9/mips-kprobes-flush_insn_slot-should-flush-only-if-probe-initialised.patch