[PATCH 4.17 178/324] bpf: hash map: decrement counter on error

Greg Kroah-Hartman
2018-08-23T08:53:18Z

From: Mauricio Vasquez B <mauricio.vasquez@polito.it>

[ Upstream commit ed2b82c03dc187018307c7c6bf9299705f3db383 ]

Decrement the number of elements in the map in case the allocation
of a new node fails.

Fixes: 6c9059817432 ("bpf: pre-allocate hash map elements")
Signed-off-by: Mauricio Vasquez B <mauricio.vasquez@polito.it>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/bpf/hashtab.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -743,13 +743,15 @@ static struct htab_elem *alloc_htab_elem
* old element will be freed immediately.
* Otherwise return an error
*/
- atomic_dec(&htab->count);
- return ERR_PTR(-E2BIG);
+ l_new = ERR_PTR(-E2BIG);
+ goto dec_count;
}
l_new = kmalloc_node(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN,
htab->map.numa_node);
- if (!l_new)
- return ERR_PTR(-ENOMEM);
+ if (!l_new) {
+ l_new = ERR_PTR(-ENOMEM);
+ goto dec_count;
+ }
}

memcpy(l_new->key, key, key_size);
@@ -762,7 +764,8 @@ static struct htab_elem *alloc_htab_elem
GFP_ATOMIC | __GFP_NOWARN);
if (!pptr) {
kfree(l_new);
- return ERR_PTR(-ENOMEM);
+ l_new = ERR_PTR(-ENOMEM);
+ goto dec_count;
}
}

@@ -776,6 +779,9 @@ static struct htab_elem *alloc_htab_elem

l_new->hash = hash;
return l_new;
+dec_count:
+ atomic_dec(&htab->count);
+ return l_new;
}

static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,