Subject: [PATCH 2/2] [v2] net/mlx5: fix possible stack overflows

From: Arnd Bergmann <[email-masked]>
Date: Mon, 19 Feb 2024 11:04:56 +0100

From: Arnd Bergmann <[email-masked]>

A couple of debug functions use a 512 byte temporary buffer and call another
function that has another buffer of the same size, which in turn exceeds the
usual warning limit for excessive stack usage:

drivers/net/ethernet/mellanox/mlx5/core/steering/dr_dbg.c:1073:1: error: stack frame size (1448) exceeds limit (1024) in 'dr_dump_start' [-Werror,-Wframe-larger-than]
dr_dump_start(struct seq_file *file, loff_t *pos)
drivers/net/ethernet/mellanox/mlx5/core/steering/dr_dbg.c:1009:1: error: stack frame size (1120) exceeds limit (1024) in 'dr_dump_domain' [-Werror,-Wframe-larger-than]
dr_dump_domain(struct seq_file *file, struct mlx5dr_domain *dmn)
drivers/net/ethernet/mellanox/mlx5/core/steering/dr_dbg.c:705:1: error: stack frame size (1104) exceeds limit (1024) in 'dr_dump_matcher_rx_tx' [-Werror,-Wframe-larger-than]
dr_dump_matcher_rx_tx(struct seq_file *file, bool is_rx,

Rework these so that each of the various code paths only ever has one of
these buffers in it, and exactly the functions that declare one have
the 'noinline_for_stack' annotation that prevents them from all being
inlined into the same caller.

Fixes: 917d1e799ddf ("net/mlx5: DR, Change SWS usage to debug fs seq_file interface")
Signed-off-by: Arnd Bergmann <[email-masked]>
---
[v2] no changes, just based on patch 1/2 but can still be applied independently
---
 .../mellanox/mlx5/core/steering/dr_dbg.c      | 82 +++++++++----------
 1 file changed, 41 insertions(+), 41 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_dbg.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_dbg.c
index be7a8481d7d2..eae04f66b8f4 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_dbg.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_dbg.c
@@ -205,12 +205,11 @@ dr_dump_hex_print(char hex[DR_HEX_SIZE], char *src, u32 size)
 }
 
 static int
-dr_dump_rule_action_mem(struct seq_file *file, const u64 rule_id,
+dr_dump_rule_action_mem(struct seq_file *file, char *buff, const u64 rule_id,
 			struct mlx5dr_rule_action_member *action_mem)
 {
 	struct mlx5dr_action *action = action_mem->action;
 	const u64 action_id = DR_DBG_PTR_TO_ID(action);
-	char buff[MLX5DR_DEBUG_DUMP_BUFF_LENGTH];
 	u64 hit_tbl_ptr, miss_tbl_ptr;
 	u32 hit_tbl_id, miss_tbl_id;
 	int ret;
@@ -505,10 +504,9 @@ dr_dump_rule_action_mem(struct seq_file *file, const u64 rule_id,
 }
 
 static int
-dr_dump_rule_mem(struct seq_file *file, struct mlx5dr_ste *ste,
+dr_dump_rule_mem(struct seq_file *file, char *buff, struct mlx5dr_ste *ste,
 		 bool is_rx, const u64 rule_id, u8 format_ver)
 {
-	char buff[MLX5DR_DEBUG_DUMP_BUFF_LENGTH];
 	char hw_ste_dump[DR_HEX_SIZE];
 	u32 mem_rec_type;
 	int ret;
@@ -540,7 +538,8 @@ dr_dump_rule_mem(struct seq_file *file, struct mlx5dr_ste *ste,
 }
 
 static int
-dr_dump_rule_rx_tx(struct seq_file *file, struct mlx5dr_rule_rx_tx *rule_rx_tx,
+dr_dump_rule_rx_tx(struct seq_file *file, char *buff,
+		   struct mlx5dr_rule_rx_tx *rule_rx_tx,
 		   bool is_rx, const u64 rule_id, u8 format_ver)
 {
 	struct mlx5dr_ste *ste_arr[DR_RULE_MAX_STES + DR_ACTION_MAX_STES];
@@ -551,7 +550,7 @@ dr_dump_rule_rx_tx(struct seq_file *file, struct mlx5dr_rule_rx_tx *rule_rx_tx,
 		return 0;
 
 	while (i--) {
-		ret = dr_dump_rule_mem(file, ste_arr[i], is_rx, rule_id,
+		ret = dr_dump_rule_mem(file, buff, ste_arr[i], is_rx, rule_id,
 				       format_ver);
 		if (ret < 0)
 			return ret;
@@ -560,7 +559,8 @@ dr_dump_rule_rx_tx(struct seq_file *file, struct mlx5dr_rule_rx_tx *rule_rx_tx,
 	return 0;
 }
 
-static int dr_dump_rule(struct seq_file *file, struct mlx5dr_rule *rule)
+static noinline_for_stack int
+dr_dump_rule(struct seq_file *file, struct mlx5dr_rule *rule)
 {
 	struct mlx5dr_rule_action_member *action_mem;
 	const u64 rule_id = DR_DBG_PTR_TO_ID(rule);
@@ -584,19 +584,19 @@ static int dr_dump_rule(struct seq_file *file, struct mlx5dr_rule *rule)
 		return ret;
 
 	if (rx->nic_matcher) {
-		ret = dr_dump_rule_rx_tx(file, rx, true, rule_id, format_ver);
+		ret = dr_dump_rule_rx_tx(file, buff, rx, true, rule_id, format_ver);
 		if (ret < 0)
 			return ret;
 	}
 
 	if (tx->nic_matcher) {
-		ret = dr_dump_rule_rx_tx(file, tx, false, rule_id, format_ver);
+		ret = dr_dump_rule_rx_tx(file, buff, tx, false, rule_id, format_ver);
 		if (ret < 0)
 			return ret;
 	}
 
 	list_for_each_entry(action_mem, &rule->rule_actions_list, list) {
-		ret = dr_dump_rule_action_mem(file, rule_id, action_mem);
+		ret = dr_dump_rule_action_mem(file, buff, rule_id, action_mem);
 		if (ret < 0)
 			return ret;
 	}
@@ -605,10 +605,10 @@ static int dr_dump_rule(struct seq_file *file, struct mlx5dr_rule *rule)
 }
 
 static int
-dr_dump_matcher_mask(struct seq_file *file, struct mlx5dr_match_param *mask,
+dr_dump_matcher_mask(struct seq_file *file, char *buff,
+		     struct mlx5dr_match_param *mask,
 		     u8 criteria, const u64 matcher_id)
 {
-	char buff[MLX5DR_DEBUG_DUMP_BUFF_LENGTH];
 	char dump[DR_HEX_SIZE];
 	int ret;
 
@@ -706,10 +706,10 @@ dr_dump_matcher_mask(struct seq_file *file, struct mlx5dr_match_param *mask,
 }
 
 static int
-dr_dump_matcher_builder(struct seq_file *file, struct mlx5dr_ste_build *builder,
+dr_dump_matcher_builder(struct seq_file *file, char *buff,
+			struct mlx5dr_ste_build *builder,
 			u32 index, bool is_rx, const u64 matcher_id)
 {
-	char buff[MLX5DR_DEBUG_DUMP_BUFF_LENGTH];
 	int ret;
 
 	memset(buff, 0, sizeof(buff));
@@ -728,11 +728,10 @@ dr_dump_matcher_builder(struct seq_file *file, struct mlx5dr_ste_build *builder,
 }
 
 static int
-dr_dump_matcher_rx_tx(struct seq_file *file, bool is_rx,
+dr_dump_matcher_rx_tx(struct seq_file *file, char *buff, bool is_rx,
 		      struct mlx5dr_matcher_rx_tx *matcher_rx_tx,
 		      const u64 matcher_id)
 {
-	char buff[MLX5DR_DEBUG_DUMP_BUFF_LENGTH];
 	enum dr_dump_rec_type rec_type;
 	u64 s_icm_addr, e_icm_addr;
 	int i, ret;
@@ -758,7 +757,7 @@ dr_dump_matcher_rx_tx(struct seq_file *file, bool is_rx,
 		return ret;
 
 	for (i = 0; i < matcher_rx_tx->num_of_builders; i++) {
-		ret = dr_dump_matcher_builder(file,
+		ret = dr_dump_matcher_builder(file, buff,
 					      &matcher_rx_tx->ste_builder[i],
 					      i, is_rx, matcher_id);
 		if (ret < 0)
@@ -768,7 +767,7 @@ dr_dump_matcher_rx_tx(struct seq_file *file, bool is_rx,
 	return 0;
 }
 
-static int
+static noinline_for_stack int
 dr_dump_matcher(struct seq_file *file, struct mlx5dr_matcher *matcher)
 {
 	struct mlx5dr_matcher_rx_tx *rx = &matcher->rx;
@@ -791,19 +790,19 @@ dr_dump_matcher(struct seq_file *file, struct mlx5dr_matcher *matcher)
 	if (ret)
 		return ret;
 
-	ret = dr_dump_matcher_mask(file, &matcher->mask,
+	ret = dr_dump_matcher_mask(file, buff, &matcher->mask,
 				   matcher->match_criteria, matcher_id);
 	if (ret < 0)
 		return ret;
 
 	if (rx->nic_tbl) {
-		ret = dr_dump_matcher_rx_tx(file, true, rx, matcher_id);
+		ret = dr_dump_matcher_rx_tx(file, buff, true, rx, matcher_id);
 		if (ret < 0)
 			return ret;
 	}
 
 	if (tx->nic_tbl) {
-		ret = dr_dump_matcher_rx_tx(file, false, tx, matcher_id);
+		ret = dr_dump_matcher_rx_tx(file, buff, false, tx, matcher_id);
 		if (ret < 0)
 			return ret;
 	}
@@ -831,11 +830,10 @@ dr_dump_matcher_all(struct seq_file *file, struct mlx5dr_matcher *matcher)
 }
 
 static int
-dr_dump_table_rx_tx(struct seq_file *file, bool is_rx,
+dr_dump_table_rx_tx(struct seq_file *file, char *buff, bool is_rx,
 		    struct mlx5dr_table_rx_tx *table_rx_tx,
 		    const u64 table_id)
 {
-	char buff[MLX5DR_DEBUG_DUMP_BUFF_LENGTH];
 	enum dr_dump_rec_type rec_type;
 	u64 s_icm_addr;
 	int ret;
@@ -858,7 +856,8 @@ dr_dump_table_rx_tx(struct seq_file *file, bool is_rx,
 	return 0;
 }
 
-static int dr_dump_table(struct seq_file *file, struct mlx5dr_table *table)
+static noinline_for_stack int
+dr_dump_table(struct seq_file *file, struct mlx5dr_table *table)
 {
 	struct mlx5dr_table_rx_tx *rx = &table->rx;
 	struct mlx5dr_table_rx_tx *tx = &table->tx;
@@ -878,14 +877,14 @@ static int dr_dump_table(struct seq_file *file, struct mlx5dr_table *table)
 		return ret;
 
 	if (rx->nic_dmn) {
-		ret = dr_dump_table_rx_tx(file, true, rx,
+		ret = dr_dump_table_rx_tx(file, buff, true, rx,
 					  DR_DBG_PTR_TO_ID(table));
 		if (ret < 0)
 			return ret;
 	}
 
 	if (tx->nic_dmn) {
-		ret = dr_dump_table_rx_tx(file, false, tx,
+		ret = dr_dump_table_rx_tx(file, buff, false, tx,
 					  DR_DBG_PTR_TO_ID(table));
 		if (ret < 0)
 			return ret;
@@ -911,10 +910,10 @@ static int dr_dump_table_all(struct seq_file *file, struct mlx5dr_table *tbl)
 }
 
 static int
-dr_dump_send_ring(struct seq_file *file, struct mlx5dr_send_ring *ring,
+dr_dump_send_ring(struct seq_file *file, char *buff,
+		  struct mlx5dr_send_ring *ring,
 		  const u64 domain_id)
 {
-	char buff[MLX5DR_DEBUG_DUMP_BUFF_LENGTH];
 	int ret;
 
 	memset(buff, 0, sizeof(buff));
@@ -933,13 +932,13 @@ dr_dump_send_ring(struct seq_file *file, struct mlx5dr_send_ring *ring,
 	return 0;
 }
 
-static noinline_for_stack int
+static int
 dr_dump_domain_info_flex_parser(struct seq_file *file,
+				char *buff,
 				const char *flex_parser_name,
 				const u8 flex_parser_value,
 				const u64 domain_id)
 {
-	char buff[MLX5DR_DEBUG_DUMP_BUFF_LENGTH];
 	int ret;
 
 	memset(buff, 0, sizeof(buff));
@@ -957,11 +956,11 @@ dr_dump_domain_info_flex_parser(struct seq_file *file,
 	return 0;
 }
 
-static noinline_for_stack int
-dr_dump_domain_info_caps(struct seq_file *file, struct mlx5dr_cmd_caps *caps,
+static int
+dr_dump_domain_info_caps(struct seq_file *file, char *buff,
+			 struct mlx5dr_cmd_caps *caps,
 			 const u64 domain_id)
 {
-	char buff[MLX5DR_DEBUG_DUMP_BUFF_LENGTH];
 	struct mlx5dr_cmd_vport_cap *vport_caps;
 	unsigned long i, vports_num;
 	int ret;
@@ -1003,34 +1002,35 @@ dr_dump_domain_info_caps(struct seq_file *file, struct mlx5dr_cmd_caps *caps,
 }
 
 static int
-dr_dump_domain_info(struct seq_file *file, struct mlx5dr_domain_info *info,
+dr_dump_domain_info(struct seq_file *file, char *buff,
+		    struct mlx5dr_domain_info *info,
 		    const u64 domain_id)
 {
 	int ret;
 
-	ret = dr_dump_domain_info_caps(file, &info->caps, domain_id);
+	ret = dr_dump_domain_info_caps(file, buff, &info->caps, domain_id);
 	if (ret < 0)
 		return ret;
 
-	ret = dr_dump_domain_info_flex_parser(file, "icmp_dw0",
+	ret = dr_dump_domain_info_flex_parser(file, buff, "icmp_dw0",
 					      info->caps.flex_parser_id_icmp_dw0,
 					      domain_id);
 	if (ret < 0)
 		return ret;
 
-	ret = dr_dump_domain_info_flex_parser(file, "icmp_dw1",
+	ret = dr_dump_domain_info_flex_parser(file, buff, "icmp_dw1",
 					      info->caps.flex_parser_id_icmp_dw1,
 					      domain_id);
 	if (ret < 0)
 		return ret;
 
-	ret = dr_dump_domain_info_flex_parser(file, "icmpv6_dw0",
+	ret = dr_dump_domain_info_flex_parser(file, buff, "icmpv6_dw0",
 					      info->caps.flex_parser_id_icmpv6_dw0,
 					      domain_id);
 	if (ret < 0)
 		return ret;
 
-	ret = dr_dump_domain_info_flex_parser(file, "icmpv6_dw1",
+	ret = dr_dump_domain_info_flex_parser(file, buff, "icmpv6_dw1",
 					      info->caps.flex_parser_id_icmpv6_dw1,
 					      domain_id);
 	if (ret < 0)
@@ -1067,12 +1067,12 @@ dr_dump_domain(struct seq_file *file, struct mlx5dr_domain *dmn)
 	if (ret)
 		return ret;
 
-	ret = dr_dump_domain_info(file, &dmn->info, domain_id);
+	ret = dr_dump_domain_info(file, buff, &dmn->info, domain_id);
 	if (ret < 0)
 		return ret;
 
 	if (dmn->info.supp_sw_steering) {
-		ret = dr_dump_send_ring(file, dmn->send_ring, domain_id);
+		ret = dr_dump_send_ring(file, buff, dmn->send_ring, domain_id);
 		if (ret < 0)
 			return ret;
 	}
-- 
2.39.2