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

From: Zhu Yanjun <[email-masked]>
Date: Thu, 15 Feb 2024 08:18:48 +0800

在 2024/2/13 18:08, Arnd Bergmann 写道:
> 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]>
> ---
>   .../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 64f4cc284aea..030a5776c937 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;
> @@ -488,10 +487,9 @@ 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;
> @@ -522,7 +520,8 @@ 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];
> @@ -533,7 +532,7 @@ 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,

Before buff is reused, I am not sure whether buff should be firstly 
zeroed or not.

Zhu Yanjun

> +		ret = dr_dump_rule_mem(file, buff, ste_arr[i], is_rx, rule_id,
>   				       format_ver);
>   		if (ret < 0)
>   			return ret;
> @@ -542,7 +541,8 @@ 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);
> @@ -565,19 +565,19 @@ 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;
>   	}
> @@ -586,10 +586,10 @@ 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;
>   
> @@ -681,10 +681,10 @@ 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;
>   
>   	ret = snprintf(buff, MLX5DR_DEBUG_DUMP_BUFF_LENGTH,
> @@ -702,11 +702,10 @@ 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;
> @@ -731,7 +730,7 @@ 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)
> @@ -741,7 +740,7 @@ 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;
> @@ -763,19 +762,19 @@ 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;
>   	}
> @@ -803,11 +802,10 @@ 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;
> @@ -829,7 +827,8 @@ 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;
> @@ -848,14 +847,14 @@ 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;
> @@ -881,10 +880,10 @@ 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;
>   
>   	ret = snprintf(buff, MLX5DR_DEBUG_DUMP_BUFF_LENGTH,
> @@ -902,13 +901,13 @@ 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;
>   
>   	ret = snprintf(buff, MLX5DR_DEBUG_DUMP_BUFF_LENGTH,
> @@ -925,11 +924,11 @@ 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;
> @@ -969,34 +968,35 @@ 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)
> @@ -1032,12 +1032,12 @@ 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;
>   	}