From: Yuntao Wang Date: Thu, 7 Apr 2022 13:04:23 +0000 (+0800) Subject: bpf: Fix excessive memory allocation in stack_map_alloc() X-Git-Tag: v5.15.73~3912 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=51f6657e94439f303c731b57734b9dc255687dff;p=platform%2Fkernel%2Flinux-rpi.git bpf: Fix excessive memory allocation in stack_map_alloc() commit b45043192b3e481304062938a6561da2ceea46a6 upstream. 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 Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220407130423.798386-1-ytcoode@gmail.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index fc0f77f..7efae3a 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -119,7 +119,6 @@ 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);