MIPS: uprobes: fix use of uninitialised variable

arch_uprobe_pre_xol needs to emulate a branch if a branch instruction
has been replaced with a breakpoint, but in fact an uninitialised local
variable was passed to the emulator routine instead of the original
instruction

Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Fixes: 40e084a506eb ('MIPS: Add uprobes support.')
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14300/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/uprobes.c b/arch/mips/kernel/uprobes.c
index 3b8accb0b4f01e9ceb6a40649a240389cc50ccc6..4c7c1558944a2a5382c4c8076866607c0064d392 100644 (file)
--- a/arch/mips/kernel/uprobes.c
+++ b/arch/mips/kernel/uprobes.c
@@ -157,7 +157,6 @@ bool is_trap_insn(uprobe_opcode_t *insn)
 int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs)
 {
        struct uprobe_task *utask = current->utask;
-       union mips_instruction insn;
 
        /*
         * Now find the EPC where to resume after the breakpoint has been
@@ -168,10 +167,10 @@ int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs)
                unsigned long epc;
 
                epc = regs->cp0_epc;
-               __compute_return_epc_for_insn(regs, insn);
+               __compute_return_epc_for_insn(regs,
+                       (union mips_instruction) aup->insn[0]);
                aup->resume_epc = regs->cp0_epc;
        }
-
        utask->autask.saved_trap_nr = current->thread.trap_nr;
        current->thread.trap_nr = UPROBE_TRAP_NR;
        regs->cp0_epc = current->utask->xol_vaddr;