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Subject[PATCH] net: mellanox: prevent resource leak on htbl
Date
According to a Coverity static analysis tool,
`drivers/net/mellanox/mlx5/core/steering/dr_rule.c#63` leaks a
`struct mlx5dr_ste_htbl *` named `new_htbl` while returning from
`dr_rule_create_collision_htbl` function.

A annotated snippet of the possible resource leak follows:

```
static struct mlx5dr_ste *
dr_rule_create_collision_htbl(struct mlx5dr_matcher *matcher,
struct mlx5dr_matcher_rx_tx *nic_matcher,
u8 *hw_ste)
/* ... */
/* ... */

/* Storage is returned from allocation function mlx5dr_ste_htbl_alloc. */
/* Assigning: new_htbl = storage returned from mlx5dr_ste_htbl_alloc(..) */
new_htbl = mlx5dr_ste_htbl_alloc(dmn->ste_icm_pool,
DR_CHUNK_SIZE_1,
MLX5DR_STE_LU_TYPE_DONT_CARE,
0);
/* Condition !new_htbl, taking false branch. */
if (!new_htbl) {
mlx5dr_dbg(dmn, "Failed allocating collision table\n");
return NULL;
}

/* One and only entry, never grows */
ste = new_htbl->ste_arr;
mlx5dr_ste_set_miss_addr(hw_ste, nic_matcher->e_anchor->chunk->icm_addr);
/* Resource new_htbl is not freed or pointed-to in mlx5dr_htbl_get */
mlx5dr_htbl_get(new_htbl);

/* Variable new_htbl going out of scope leaks the storage it points to. */
return ste;
```

There's a caller of this function which does refcounting and free'ing by
itself but that function also skips free'ing `new_htbl` due to missing
jump to error label. (referring to `dr_rule_create_collision_entry lines
75-77. They don't jump to `free_tbl`)

Added a `kfree(new_htbl)` just before returning `ste` pointer to fix the
leak.

Signed-off-by: Cengiz Can <cengiz@kernel.wtf>
---

This might be totally breaking the refcounting logic in the file so
please provide any feedback so I can evolve this into something more
suitable.

For the record, Coverity scan id is CID 1457773.

drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
index e4cff7abb348..047b403c61db 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
@@ -60,6 +60,8 @@ dr_rule_create_collision_htbl(struct mlx5dr_matcher *matcher,
mlx5dr_ste_set_miss_addr(hw_ste, nic_matcher->e_anchor->chunk->icm_addr);
mlx5dr_htbl_get(new_htbl);

+ kfree(new_htbl);
+
return ste;
}

--
2.24.1
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