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Date: Tue, 7 Jun 2022 18:59:53 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Yuntao Wang <ytcoode@...il.com>, Daniel Borkmann <daniel@...earbox.net>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 5.10 136/452] bpf: Fix excessive memory allocation in stack_map_alloc() From: Yuntao Wang <ytcoode@...il.com> [ Upstream commit b45043192b3e481304062938a6561da2ceea46a6 ] The 'n_buckets * (value_size + sizeof(struct stack_map_bucket))' part of the allocated memory for 'smap' is never used after the memlock accounting was removed, thus get rid of it. [ Note, Daniel: Commit b936ca643ade ("bpf: rework memlock-based memory accounting for maps") moved `cost += n_buckets * (value_size + sizeof(struct stack_map_bucket))` up and therefore before the bpf_map_area_alloc() allocation, sigh. In a later step commit c85d69135a91 ("bpf: move memory size checks to bpf_map_charge_init()"), and the overflow checks of `cost >= U32_MAX - PAGE_SIZE` moved into bpf_map_charge_init(). And then 370868107bf6 ("bpf: Eliminate rlimit-based memory accounting for stackmap maps") finally removed the bpf_map_charge_init(). Anyway, the original code did the allocation same way as /after/ this fix. ] Fixes: b936ca643ade ("bpf: rework memlock-based memory accounting for maps") Signed-off-by: Yuntao Wang <ytcoode@...il.com> Signed-off-by: Daniel Borkmann <daniel@...earbox.net> Link: https://lore.kernel.org/bpf/20220407130423.798386-1-ytcoode@gmail.com Signed-off-by: Sasha Levin <sashal@...nel.org> --- kernel/bpf/stackmap.c | 1 - 1 file changed, 1 deletion(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 4575d2d60cb1..c19e669afba0 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -121,7 +121,6 @@ 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)); err = bpf_map_charge_init(&mem, cost); if (err) return ERR_PTR(err); -- 2.35.1
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