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

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

[Björn Töpel]

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@kernel.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

Re: [PATCH bpf] riscv, bpf: Fix potential NULL dereference

[Jakub Kicinski]

On Thu, 28 Oct 2021 14:51:15 +0200 Björn Töpel wrote:
> 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@kernel.org>

Looks pretty trivial so applied to net with Daniel's off-list blessing.

Re: [PATCH bpf] riscv, bpf: Fix potential NULL dereference

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 28 Oct 2021 14:51:15 +0200 you wrote:
> 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@kernel.org>
> 
> [...]

Here is the summary with links:
  - [bpf] riscv, bpf: Fix potential NULL dereference
    https://git.kernel.org/netdev/net/c/27de809a3d83

You are awesome, thank you!
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