[PATCH AUTOSEL for 4.4 137/167] MIPS: kprobes: flush_insn_slot should flush only if probe initialised

Sasha Levin
2018-03-19T17:08:17Z

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>
---
arch/mips/include/asm/kprobes.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/mips/include/asm/kprobes.h b/arch/mips/include/asm/kprobes.h
index daba1f9a4f79..174aedce3167 100644
--- a/arch/mips/include/asm/kprobes.h
+++ b/arch/mips/include/asm/kprobes.h
@@ -40,7 +40,8 @@ typedef union mips_instruction kprobe_opcode_t;

#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)
--
2.14.1