2017-09-27 08:15:25

by Matt Redfearn

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Subject: [PATCH] MIPS: bpf: Fix uninitialised target compiler error

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 <[email protected]>
Fixes: b6bd53f9c4e8 ("MIPS: Add missing file for eBPF JIT.")
Cc: <[email protected]> # v4.13+
---

arch/mips/net/ebpf_jit.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 7646891c4e9b..01b7a87ea678 100644
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c
@@ -667,7 +667,7 @@ 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;
int bpf_op = BPF_OP(insn->code);
--
2.7.4