MIPS: bpf: Fix uninitialised target compiler error

BugLink: http://bugs.launchpad.net/bugs/1724669
commit 94c3390ab84a6b449accc7351ffda4a0c17bdb92 upstream.

Compiling ebpf_jit.c with gcc 4.9 results in a (likely spurious)
compiler warning, as gcc has detected that the variable "target" may be
used uninitialised. Since -Werror is active, this is treated as an error
and causes a kernel build failure whenever CONFIG_MIPS_EBPF_JIT is
enabled.

arch/mips/net/ebpf_jit.c: In function 'build_one_insn':
arch/mips/net/ebpf_jit.c:1118:80: error: 'target' may be used
uninitialized in this function [-Werror=maybe-uninitialized]
    emit_instr(ctx, j, target);
                                                                                ^
cc1: all warnings being treated as errors

Fix this by initialising "target" to 0. If it really is used
uninitialised this would result in a jump to 0 and a detectable run time
failure.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Fixes: b6bd53f9c4e8 ("MIPS: Add missing file for eBPF JIT.")
Cc: James Hogan <james.hogan@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17375/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 3f87b96da5c4cba03aa2cff0f506f72626d99dbf..401776f9228865b23bbfa8466cc4101b3761394e 100644 (file)
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c
@@ -679,7 +679,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
 {
        int src, dst, r, td, ts, mem_off, b_off;
        bool need_swap, did_move, cmp_eq;
-       unsigned int target;
+       unsigned int target = 0;
        u64 t64;
        s64 t64s;