[PATCH] riscv: kprobes: fix placement in arch_prepare_ss_slot

[Ben Dooks]

The second patch_text_nosync() in arch_prepare_ss_slot should be pointing
after the first instruction, however p->ainsn.api.insn is a pointer to a
probe_opcode_t which is 4 bytes... this means an instruction of length 2
moves the pointer by 8 bytes.

This means a kprobe may fail to work and recurse into the bad instruction
handler (which then itself fails as the original lock still seems to be
held?)

Fixes: b1756750a397f36ddc857 ("riscv: kprobes: Use patch_text_nosync() for insn slots")
Signed-off-by: Ben Dooks <ben.dooks at codethink.co.uk>
Cc: Samuel Holland <samuel.holland at sifive.com>
---
 arch/riscv/kernel/probes/kprobes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
index 380a0e8cecc0..c0738d6c6498 100644
--- a/arch/riscv/kernel/probes/kprobes.c
+++ b/arch/riscv/kernel/probes/kprobes.c
@@ -30,7 +30,7 @@ static void __kprobes arch_prepare_ss_slot(struct kprobe *p)
 	p->ainsn.api.restore = (unsigned long)p->addr + len;
 
 	patch_text_nosync(p->ainsn.api.insn, &p->opcode, len);
-	patch_text_nosync(p->ainsn.api.insn + len, &insn, GET_INSN_LENGTH(insn));
+	patch_text_nosync((void *)p->ainsn.api.insn + len, &insn, GET_INSN_LENGTH(insn));
 }
 
 static void __kprobes arch_prepare_simulate(struct kprobe *p)
-- 
2.37.2.352.g3c44437643