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netfilter: nf_tables: fix nft_counters_enabled underflow at nf_tables_addchain()

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[ Upstream commit 921ebde3c0 ]

syzbot is reporting underflow of nft_counters_enabled counter at
nf_tables_addchain() [1], for commit 43eb8949cf ("netfilter:
nf_tables: do not leave chain stats enabled on error") missed that
nf_tables_chain_destroy() after nft_basechain_init() in the error path of
nf_tables_addchain() decrements the counter because nft_basechain_init()
makes nft_is_base_chain() return true by setting NFT_CHAIN_BASE flag.

Increment the counter immediately after returning from
nft_basechain_init().

Link:  https://syzkaller.appspot.com/bug?extid=b5d82a651b71cd8a75ab [1]
Reported-by: syzbot <syzbot+b5d82a651b71cd8a75ab@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+b5d82a651b71cd8a75ab@syzkaller.appspotmail.com>
Fixes: 43eb8949cf ("netfilter: nf_tables: do not leave chain stats enabled on error")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Tetsuo Handa 2022-09-12 21:41:00 +09:00 • committed by Greg Kroah-Hartman
commit 710e3f526b
1 changed files with 3 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

7
net/netfilter/nf_tables_api.c
View file

@ -2001,7 +2001,6 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
u8 policy, u32 flags)
{
const struct nlattr * const *nla = ctx->nla;
struct nft_stats __percpu *stats = NULL;
struct nft_table *table = ctx->table;
struct nft_base_chain *basechain;
struct net *net = ctx->net;
@ -2015,6 +2014,7 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
return -EOVERFLOW;
if (nla[NFTA_CHAIN_HOOK]) {
struct nft_stats __percpu *stats = NULL;
struct nft_chain_hook hook;
if (flags & NFT_CHAIN_BINDING)
@ -2047,6 +2047,8 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
kfree(basechain);
return err;
}
if (stats)
static_branch_inc(&nft_counters_enabled);
} else {
if (flags & NFT_CHAIN_BASE)
return -EINVAL;
@ -2121,9 +2123,6 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
goto err_unregister_hook;
}
if (stats)
static_branch_inc(&nft_counters_enabled);
table->use++;
return 0;