The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From b45043192b3e481304062938a6561da2ceea46a6 Mon Sep 17 00:00:00 2001
From: Yuntao Wang <ytcoode@xxxxxxxxx>
Date: Thu, 7 Apr 2022 21:04:23 +0800
Subject: [PATCH] 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 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@xxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20220407130423.798386-1-ytcoode@xxxxxxxxx
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);
