linux-kernel - [PATCH bpf-next] bpf: Fix excessive memory allocation in stack_map

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Date:   Thu,  7 Apr 2022 21:04:23 +0800
From:   Yuntao Wang <ytcoode@...il.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>
Cc:     Martin KaFai Lau <kafai@...com>, Song Liu <songliubraving@...com>,
        Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yuntao Wang <ytcoode@...il.com>
Subject: [PATCH bpf-next] bpf: Fix excessive memory allocation in stack_map_alloc()

The 'n_buckets * (value_size + sizeof(struct stack_map_bucket))' part of
the allocated memory for 'smap' is never used, get rid of it.

Fixes: b936ca643ade ("bpf: rework memlock-based memory accounting for maps")
Signed-off-by: Yuntao Wang <ytcoode@...il.com>
---
 kernel/bpf/stackmap.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index 6131b4a19572..1dd5266fbebb 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -100,7 +100,6 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
 		return ERR_PTR(-E2BIG);
 
 	cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);
-	cost += n_buckets * (value_size + sizeof(struct stack_map_bucket));
 	smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr));
 	if (!smap)
 		return ERR_PTR(-ENOMEM);
-- 
2.35.0.rc2