diff mbox series

[net-next,11/11] netfilter: nf_tables: must hold rcu read lock while iterating object type list

Message ID 20241106234625.168468-12-pablo@netfilter.org (mailing list archive)
State Accepted
Commit cddc04275f95ca3b18da5c0fb111705ac173af89
Delegated to: Netdev Maintainers
Headers show
Series [net-next,01/11] netfilter: Make legacy configs user selectable | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 3 maintainers not CCed: horms@kernel.org kadlec@netfilter.org coreteam@netfilter.org
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
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: 14 this patch: 14
netdev/checkpatch warning WARNING: line length of 87 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 5 this patch: 5
netdev/source_inline success Was 0 now: 0
netdev/contest fail net-next-2024-11-07--03-00 (tests: 786)

Commit Message

Pablo Neira Ayuso Nov. 6, 2024, 11:46 p.m. UTC 
From: Florian Westphal <fw@strlen.de>

Update of stateful object triggers:
WARNING: suspicious RCU usage
net/netfilter/nf_tables_api.c:7759 RCU-list traversed in non-reader section!!

other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by nft/3060:
 #0: ffff88810f0578c8 (&nft_net->commit_mutex){+.+.}-{4:4}, [..]

... but this list is not protected by the transaction mutex but the
nfnl nftables subsystem mutex.

Switch to nft_obj_type_get which will acquire rcu read lock,
bump refcount, and returns the result.

v3: Dan Carpenter points out nft_obj_type_get returns error pointer, not
NULL, on error.

Fixes: dad3bdeef45f ("netfilter: nf_tables: fix memory leak during stateful obj update").
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index de8e48a5c62d..b7a817e483aa 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -7809,9 +7809,7 @@  static int nf_tables_updobj(const struct nft_ctx *ctx,
 	struct nft_trans *trans;
 	int err = -ENOMEM;
 
-	if (!try_module_get(type->owner))
-		return -ENOENT;
-
+	/* caller must have obtained type->owner reference. */
 	trans = nft_trans_alloc(ctx, NFT_MSG_NEWOBJ,
 				sizeof(struct nft_trans_obj));
 	if (!trans)
@@ -7879,15 +7877,16 @@  static int nf_tables_newobj(struct sk_buff *skb, const struct nfnl_info *info,
 		if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
 			return -EOPNOTSUPP;
 
-		type = __nft_obj_type_get(objtype, family);
-		if (WARN_ON_ONCE(!type))
-			return -ENOENT;
-
 		if (!obj->ops->update)
 			return 0;
 
+		type = nft_obj_type_get(net, objtype, family);
+		if (WARN_ON_ONCE(IS_ERR(type)))
+			return PTR_ERR(type);
+
 		nft_ctx_init(&ctx, net, skb, info->nlh, family, table, NULL, nla);
 
+		/* type->owner reference is put when transaction object is released. */
 		return nf_tables_updobj(&ctx, type, nla[NFTA_OBJ_DATA], obj);
 	}