[dpdk-dev] [PATCH] net/mlx5: fix pattern expansion in RSS flow rules

[Gregory Etelson <getelson@nvidia.com>]

Flow rule pattern may be implicitly expanded by the PMD if the rule
has RSS flow action. The expansion adds network headers to the
original pattern. The new pattern lists all network levels that
participate in the rule RSS action.

The patch validates that buffer for expanded pattern has enough bytes
for new flow items.

Fixes: c7870bfe09dc ("ethdev: move RSS expansion code to mlx5 driver")

Cc: stable@dpdk.org
Signed-off-by: Gregory Etelson <getelson@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
 drivers/net/mlx5/mlx5_flow.c | 63 +++++++++++++++++++-----------------
 1 file changed, 33 insertions(+), 30 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_flow.c b/drivers/net/mlx5/mlx5_flow.c
index c5d4a95a8f..159e84bfab 100644
--- a/drivers/net/mlx5/mlx5_flow.c
+++ b/drivers/net/mlx5/mlx5_flow.c
@@ -264,6 +264,7 @@ mlx5_flow_expand_rss_item_complete(const struct rte_flow_item *item)
  *   set, the following errors are defined:
  *
  *   -E2BIG: graph-depth @p graph is too deep.
+ *   -EINVAL: @p size has not enough space for expanded pattern.
  */
 static int
 mlx5_flow_expand_rss(struct mlx5_flow_expand_rss *buf, size_t size,
@@ -290,12 +291,12 @@ mlx5_flow_expand_rss(struct mlx5_flow_expand_rss *buf, size_t size,
 	memset(&missed_item, 0, sizeof(missed_item));
 	lsize = offsetof(struct mlx5_flow_expand_rss, entry) +
 		MLX5_RSS_EXP_ELT_N * sizeof(buf->entry[0]);
-	if (lsize <= size) {
-		buf->entry[0].priority = 0;
-		buf->entry[0].pattern = (void *)&buf->entry[MLX5_RSS_EXP_ELT_N];
-		buf->entries = 0;
-		addr = buf->entry[0].pattern;
-	}
+	if (lsize > size)
+		return -EINVAL;
+	buf->entry[0].priority = 0;
+	buf->entry[0].pattern = (void *)&buf->entry[MLX5_RSS_EXP_ELT_N];
+	buf->entries = 0;
+	addr = buf->entry[0].pattern;
 	for (item = pattern; item->type != RTE_FLOW_ITEM_TYPE_END; item++) {
 		if (!mlx5_flow_is_rss_expandable_item(item)) {
 			user_pattern_size += sizeof(*item);
@@ -313,12 +314,12 @@ mlx5_flow_expand_rss(struct mlx5_flow_expand_rss *buf, size_t size,
 	}
 	user_pattern_size += sizeof(*item); /* Handle END item. */
 	lsize += user_pattern_size;
+	if (lsize > size)
+		return -EINVAL;
 	/* Copy the user pattern in the first entry of the buffer. */
-	if (lsize <= size) {
-		rte_memcpy(addr, pattern, user_pattern_size);
-		addr = (void *)(((uintptr_t)addr) + user_pattern_size);
-		buf->entries = 1;
-	}
+	rte_memcpy(addr, pattern, user_pattern_size);
+	addr = (void *)(((uintptr_t)addr) + user_pattern_size);
+	buf->entries = 1;
 	/* Start expanding. */
 	memset(flow_items, 0, sizeof(flow_items));
 	user_pattern_size -= sizeof(*item);
@@ -348,7 +349,9 @@ mlx5_flow_expand_rss(struct mlx5_flow_expand_rss *buf, size_t size,
 		elt = 2; /* missed item + item end. */
 		node = next;
 		lsize += elt * sizeof(*item) + user_pattern_size;
-		if ((node->rss_types & types) && lsize <= size) {
+		if (lsize > size)
+			return -EINVAL;
+		if (node->rss_types & types) {
 			buf->entry[buf->entries].priority = 1;
 			buf->entry[buf->entries].pattern = addr;
 			buf->entries++;
@@ -367,6 +370,7 @@ mlx5_flow_expand_rss(struct mlx5_flow_expand_rss *buf, size_t size,
 	while (node) {
 		flow_items[stack_pos].type = node->type;
 		if (node->rss_types & types) {
+			size_t n;
 			/*
 			 * compute the number of items to copy from the
 			 * expansion and copy it.
@@ -376,24 +380,23 @@ mlx5_flow_expand_rss(struct mlx5_flow_expand_rss *buf, size_t size,
 			elt = stack_pos + 2;
 			flow_items[stack_pos + 1].type = RTE_FLOW_ITEM_TYPE_END;
 			lsize += elt * sizeof(*item) + user_pattern_size;
-			if (lsize <= size) {
-				size_t n = elt * sizeof(*item);
-
-				buf->entry[buf->entries].priority =
-					stack_pos + 1 + missed;
-				buf->entry[buf->entries].pattern = addr;
-				buf->entries++;
-				rte_memcpy(addr, buf->entry[0].pattern,
-					   user_pattern_size);
-				addr = (void *)(((uintptr_t)addr) +
-						user_pattern_size);
-				rte_memcpy(addr, &missed_item,
-					   missed * sizeof(*item));
-				addr = (void *)(((uintptr_t)addr) +
-					missed * sizeof(*item));
-				rte_memcpy(addr, flow_items, n);
-				addr = (void *)(((uintptr_t)addr) + n);
-			}
+			if (lsize > size)
+				return -EINVAL;
+			n = elt * sizeof(*item);
+			buf->entry[buf->entries].priority =
+				stack_pos + 1 + missed;
+			buf->entry[buf->entries].pattern = addr;
+			buf->entries++;
+			rte_memcpy(addr, buf->entry[0].pattern,
+				   user_pattern_size);
+			addr = (void *)(((uintptr_t)addr) +
+					user_pattern_size);
+			rte_memcpy(addr, &missed_item,
+				   missed * sizeof(*item));
+			addr = (void *)(((uintptr_t)addr) +
+				missed * sizeof(*item));
+			rte_memcpy(addr, flow_items, n);
+			addr = (void *)(((uintptr_t)addr) + n);
 		}
 		/* Go deeper. */
 		if (!node->optional && node->next) {
-- 
2.31.1