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From: Matt Redfearn <matt.redfearn@imgtec.com>
To: Ralf Baechle <ralf@linux-mips.org>, James Hogan <james.hogan@imgtec.com>
Cc: <linux-mips@linux-mips.org>, David Daney <david.daney@cavium.com>,
	Matt Redfearn <matt.redfearn@imgtec.com>,
	"# v4 . 13+" <stable@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Colin Ian King <colin.king@canonical.com>,
	Daniel Borkmann <daniel@iogearbox.net>
Subject: [PATCH] MIPS: bpf: Fix uninitialised target compiler error
Date: Wed, 27 Sep 2017 09:14:58 +0100	[thread overview]
Message-ID: <1506500098-3723-1-git-send-email-matt.redfearn@imgtec.com> (raw)
In-Reply-To: <31051d4e-95a1-ec81-7e9e-5cf0f3d752df@imgtec.com>

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: <stable@vger.kernel.org> # 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

           reply	other threads:[~2017-09-27  8:15 UTC|newest]

Thread overview: expand[flat|nested]  mbox.gz  Atom feed
 [parent not found: <31051d4e-95a1-ec81-7e9e-5cf0f3d752df@imgtec.com>]

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