pipeline: fix emit instruction for invalid headers

[ upstream commit 775be5b ]

Fix the emit instruction for the pathological case of all headers to
be emitted being invalid. In this case, the for loop was essentially
skipped and the last emitted header (or an invalid memory location)
getting corrupted by setting its size to 0 through the assignment to
ho->n_bytes right after the for loop.

Fixes: d60dbdc ("pipeline: create inline functions for emit instruction")

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Signed-off-by: Venkata Suresh Kumar P <venkata.suresh.kumar.p@intel.com>
Signed-off-by: Yogesh Jangra <yogesh.jangra@intel.com>

lib/pipeline/rte_swx_pipeline_internal.h

@@ -1820,9 +1820,9 @@ __instr_hdr_emit_many_exec(struct rte_swx_pipeline *p __rte_unused,
 {
 	uint64_t valid_headers = t->valid_headers;
 	uint32_t n_headers_out = t->n_headers_out;
-	struct header_out_runtime *ho = &t->headers_out[n_headers_out - 1];
+	struct header_out_runtime *ho = NULL;
 	uint8_t *ho_ptr = NULL;
-	uint32_t ho_nbytes = 0, first = 1, i;
+	uint32_t ho_nbytes = 0, i;
 
 	for (i = 0; i < n_emit; i++) {
 		uint32_t header_id = ip->io.hdr.header_id[i];
@@ -1834,18 +1834,21 @@ __instr_hdr_emit_many_exec(struct rte_swx_pipeline *p __rte_unused,
 
 		uint8_t *hi_ptr = t->structs[struct_id];
 
-		if (!MASK64_BIT_GET(valid_headers, header_id))
+		if (!MASK64_BIT_GET(valid_headers, header_id)) {
+			TRACE("[Thread %2u]: emit header %u (invalid)\n",
+			      p->thread_id,
+			      header_id);
+
 			continue;
+		}
 
-		TRACE("[Thread %2u]: emit header %u\n",
+		TRACE("[Thread %2u]: emit header %u (valid)\n",
 		      p->thread_id,
 		      header_id);
 
 		/* Headers. */
-		if (first) {
-			first = 0;
-
-			if (!t->n_headers_out) {
+		if (!ho) {
+			if (!n_headers_out) {
 				ho = &t->headers_out[0];
 
 				ho->ptr0 = hi_ptr0;
@@ -1858,6 +1861,8 @@ __instr_hdr_emit_many_exec(struct rte_swx_pipeline *p __rte_unused,
 
 				continue;
 			} else {
+				ho = &t->headers_out[n_headers_out - 1];
+
 				ho_ptr = ho->ptr;
 				ho_nbytes = ho->n_bytes;
 			}
@@ -1879,7 +1884,8 @@ __instr_hdr_emit_many_exec(struct rte_swx_pipeline *p __rte_unused,
 		}
 	}
 
-	ho->n_bytes = ho_nbytes;
+	if (ho)
+		ho->n_bytes = ho_nbytes;
 	t->n_headers_out = n_headers_out;
 }