[PATCH bpf 1/1] bpf: test_run: fix ctx leak in bpf_prog_test_run_xdp error path

[Shardul Bankar]

Fix a memory leak in bpf_prog_test_run_xdp() where the context buffer
allocated by bpf_ctx_init() is not freed when the function returns early
due to a data size check.

On the failing path:
  ctx = bpf_ctx_init(...);
  if (kattr->test.data_size_in - meta_sz < ETH_HLEN)
      return -EINVAL;

The early return bypasses the cleanup label that kfree()s ctx, leading to a
leak detectable by kmemleak under fuzzing. Change the return to jump to the
existing free_ctx label.

Fixes: fe9544ed1a2e ("bpf: Support specifying linear xdp packet data size for BPF_PROG_TEST_RUN")
Reported-by: BPF Runtime Fuzzer (BRF)
Signed-off-by: Shardul Bankar <shardulsb08@xxxxxxxxx>
---
 net/bpf/test_run.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index dfb03ee0bb62..1782e83de2cb 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -1269,7 +1269,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 		goto free_ctx;
 
 	if (kattr->test.data_size_in - meta_sz < ETH_HLEN)
-		return -EINVAL;
+		goto free_ctx;
 
 	data = bpf_test_init(kattr, linear_sz, max_linear_sz, headroom, tailroom);
 	if (IS_ERR(data)) {
-- 
2.34.1