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fix: grpc client call panic #2981

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fix: grpc client call panic #2981

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0a00ebb
fix: try to fix grpc client call panic
Oct 27, 2025
d5a7a17
Merge branch 'main' into hotfix_grpc_call_panic
quanbisen Oct 30, 2025
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62 changes: 51 additions & 11 deletions internal/pkg/instrumentation/bpf/google.golang.org/grpc/client/bpf/probe.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,22 @@ struct {
__uint(max_entries, MAX_CONCURRENT);
} streamid_to_span_contexts SEC(".maps");

// Per-stream storage for traceparent header strings
// Stored in BPF maps to ensure data persists until gRPC finishes encoding
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, u32);
__type(value, char[W3C_KEY_LENGTH]);
__uint(max_entries, MAX_CONCURRENT);
} traceparent_keys SEC(".maps");

struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, u32);
__type(value, char[SPAN_CONTEXT_STRING_SIZE]);
__uint(max_entries, MAX_CONCURRENT);
} traceparent_values SEC(".maps");

// Injected in init
volatile const u64 clientconn_target_ptr_pos;
volatile const u64 httpclient_nextid_pos;
Expand Down Expand Up @@ -180,24 +196,48 @@ int uprobe_LoopyWriter_HeaderHandler(struct pt_regs *ctx) {
struct span_context current_span_context = {};
bpf_probe_read(&current_span_context, sizeof(current_span_context), sc_ptr);

char tp_key[11] = "traceparent";
struct go_string key_str = write_user_go_string(tp_key, sizeof(tp_key));
if (key_str.len == 0) {
// Store traceparent key and value in BPF maps for persistence
char tp_key[W3C_KEY_LENGTH] = "traceparent";
bpf_map_update_elem(&traceparent_keys, &stream_id, tp_key, BPF_ANY);

char tp_value[SPAN_CONTEXT_STRING_SIZE];
span_context_to_w3c_string(&current_span_context, tp_value);
bpf_map_update_elem(&traceparent_values, &stream_id, tp_value, BPF_ANY);

// Get pointers to the persistent BPF map storage
char *key_storage = bpf_map_lookup_elem(&traceparent_keys, &stream_id);
char *val_storage = bpf_map_lookup_elem(&traceparent_values, &stream_id);

if (key_storage == NULL || val_storage == NULL) {
bpf_printk("failed to lookup traceparent storage");
goto done;
}

// Copy strings to userspace from BPF map storage
void *key_ptr = write_target_data(key_storage, W3C_KEY_LENGTH);
if (key_ptr == NULL) {
bpf_printk("key write failed, aborting ebpf probe");
goto done;
}

// Write headers
char val[SPAN_CONTEXT_STRING_SIZE];
span_context_to_w3c_string(&current_span_context, val);
struct go_string val_str = write_user_go_string(val, sizeof(val));
if (val_str.len == 0) {
void *val_ptr = write_target_data(val_storage, SPAN_CONTEXT_STRING_SIZE);
if (val_ptr == NULL) {
bpf_printk("val write failed, aborting ebpf probe");
goto done;
}
struct hpack_header_field hf = {};
hf.name = key_str;
hf.value = val_str;

// Build hpack header field
struct hpack_header_field hf = {
.name = {
.str = key_ptr,
.len = W3C_KEY_LENGTH,
},
.value = {
.str = val_ptr,
.len = SPAN_CONTEXT_STRING_SIZE,
},
.sensitive = false,
};
append_item_to_slice(&hf, sizeof(hf), (void *)(headerFrame_ptr + (headerFrame_hf_pos)));
done:
bpf_map_delete_elem(&streamid_to_span_contexts, &stream_id);
Expand Down