diff mbox series

[net,2/5] netfilter: nf_tables: fix nft_counters_enabled underflow at nf_tables_addchain()

Message ID 20220921073825.4658-3-fw@strlen.de (mailing list archive)
State Accepted
Commit 921ebde3c0d22c8cba74ce8eb3cc4626abff1ccd
Delegated to: Netdev Maintainers
Headers show
Series [net,1/5] netfilter: conntrack: remove nf_conntrack_helper documentation | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Pull request is its own cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 16 this patch: 16
netdev/cc_maintainers fail 1 blamed authors not CCed: pablo@netfilter.org; 3 maintainers not CCed: pablo@netfilter.org coreteam@netfilter.org kadlec@netfilter.org
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 16 this patch: 16
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 31 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Florian Westphal Sept. 21, 2022, 7:38 a.m. UTC 
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

syzbot is reporting underflow of nft_counters_enabled counter at
nf_tables_addchain() [1], for commit 43eb8949cfdffa76 ("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: 43eb8949cfdffa76 ("netfilter: nf_tables: do not leave chain stats enabled on error")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nf_tables_api.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 816052089b33..e062754dc6cc 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2197,7 +2197,6 @@  static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
 			      struct netlink_ext_ack *extack)
 {
 	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;
@@ -2212,6 +2211,7 @@  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)
@@ -2245,6 +2245,8 @@  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;
@@ -2319,9 +2321,6 @@  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;