netdev - [PATCH bpf] riscv, bpf: Fix potential NULL dereference

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Message-Id: <20211028125115.514587-1-bjorn@kernel.org>
Date:   Thu, 28 Oct 2021 14:51:15 +0200
From:   Björn Töpel <bjorn@...nel.org>
To:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     Björn Töpel <bjorn@...nel.org>,
        linux-riscv@...ts.infradead.org
Subject: [PATCH bpf] riscv, bpf: Fix potential NULL dereference

The bpf_jit_binary_free() function requires a non-NULL argument. When
the RISC-V BPF JIT fails to converge in NR_JIT_ITERATIONS steps,
jit_data->header will be NULL, which triggers a NULL
dereference. Avoid this by checking the argument, prior calling the
function.

Fixes: ca6cb5447cec ("riscv, bpf: Factor common RISC-V JIT code")
Signed-off-by: Björn Töpel <bjorn@...nel.org>
---
 arch/riscv/net/bpf_jit_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/net/bpf_jit_core.c b/arch/riscv/net/bpf_jit_core.c
index 0fee2cbaaf53..753d85bdfad0 100644
--- a/arch/riscv/net/bpf_jit_core.c
+++ b/arch/riscv/net/bpf_jit_core.c
@@ -125,7 +125,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
 
 	if (i == NR_JIT_ITERATIONS) {
 		pr_err("bpf-jit: image did not converge in <%d passes!\n", i);
-		bpf_jit_binary_free(jit_data->header);
+		if (jit_data->header)
+			bpf_jit_binary_free(jit_data->header);
 		prog = orig_prog;
 		goto out_offset;
 	}

base-commit: 72f898ca0ab85fde6facf78b14d9f67a4a7b32d1
-- 
2.32.0