MIPS: uprobes: fix use of uninitialised variable

commit ca86c9ef2b322ebf24772009fdea037688cbdac1 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/mips/kernel/uprobes.c b/arch/mips/kernel/uprobes.c
index c01ff4a95dc4b158e741b930f75bbe96e2f4e4fb..4e7b89f2e244ef00f0290892b09aba98b6827f28 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;