[PATCH] [v3] net/mlx5: fix possible stack overflows

From: Arnd Bergmann
Date: Wed Mar 20 2024 - 14:08:50 EST

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From: Arnd Bergmann <arnd@xxxxxxxx>

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")
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Link: https://lore.kernel.org/all/20240219100506.648089-1-arnd@xxxxxxxxxx/
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
[v3] no changes, sending again without a second patch
[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 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,
+ 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;
}
--
2.39.2

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