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netfilter: nf_tables: must hold rcu read lock while iterating object type list

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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: dad3bdeef4 ("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>
This commit is contained in:
Florian Westphal 2024-11-04 10:41:19 +01:00 committed by Pablo Neira Ayuso
parent ee666a541e
commit cddc04275f
1 changed files with 6 additions and 7 deletions
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13
net/netfilter/nf_tables_api.c
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@ -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);
}