| Message ID | 1422603994-5836-4-git-send-email-kaber@trash.net |
|---|---|
| State | Awaiting Upstream, archived |
| Delegated to: | David Miller |
| Headers | show |
Hi Patrick, On Fri, Jan 30, 2015 at 07:46:28AM +0000, Patrick McHardy wrote: > Fix a race condition and unnecessary locking: > > * the root rb_node must only be accessed under the lock in nft_rbtree_lookup() > * the lock is not needed in lookup functions in netlink contexts > > Signed-off-by: Patrick McHardy <kaber@trash.net> > --- > net/netfilter/nft_rbtree.c | 12 +++--------- > 1 file changed, 3 insertions(+), 9 deletions(-) > > diff --git a/net/netfilter/nft_rbtree.c b/net/netfilter/nft_rbtree.c > index 46214f2..417796f 100644 > --- a/net/netfilter/nft_rbtree.c > +++ b/net/netfilter/nft_rbtree.c > @@ -37,10 +37,11 @@ static bool nft_rbtree_lookup(const struct nft_set *set, > { > const struct nft_rbtree *priv = nft_set_priv(set); > const struct nft_rbtree_elem *rbe, *interval = NULL; > - const struct rb_node *parent = priv->root.rb_node; > + const struct rb_node *parent; > int d; > > spin_lock_bh(&nft_rbtree_lock); > + parent = priv->root.rb_node; Good catch. > while (parent != NULL) { > rbe = rb_entry(parent, struct nft_rbtree_elem, node); > > @@ -158,7 +159,6 @@ static int nft_rbtree_get(const struct nft_set *set, struct nft_set_elem *elem) > struct nft_rbtree_elem *rbe; > int d; > > - spin_lock_bh(&nft_rbtree_lock); > while (parent != NULL) { > rbe = rb_entry(parent, struct nft_rbtree_elem, node); > > @@ -173,11 +173,9 @@ static int nft_rbtree_get(const struct nft_set *set, struct nft_set_elem *elem) > !(rbe->flags & NFT_SET_ELEM_INTERVAL_END)) > nft_data_copy(&elem->data, rbe->data); > elem->flags = rbe->flags; > - spin_unlock_bh(&nft_rbtree_lock); > return 0; > } > } > - spin_unlock_bh(&nft_rbtree_lock); > return -ENOENT; this chunk looks fine to me, we always hold the nfnetlink mutex. > } > @@ -190,7 +188,6 @@ static void nft_rbtree_walk(const struct nft_ctx *ctx, > struct nft_set_elem elem; > struct rb_node *node; > > - spin_lock_bh(&nft_rbtree_lock); > for (node = rb_first(&priv->root); node != NULL; node = rb_next(node)) { > if (iter->count < iter->skip) > goto cont; > @@ -203,14 +200,11 @@ static void nft_rbtree_walk(const struct nft_ctx *ctx, > elem.flags = rbe->flags; > > iter->err = iter->fn(ctx, set, iter, &elem); > - if (iter->err < 0) { > - spin_unlock_bh(&nft_rbtree_lock); > + if (iter->err < 0) > return; > - } > cont: > iter->count++; > } > - spin_unlock_bh(&nft_rbtree_lock); > } > I think that _walk still needs the lock there. This is called from nf_tables_dump_set() for each recvmsg() in netlink, and IIRC unlike rtnetlink the dump path in nfnetlink is lockless. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/netfilter/nft_rbtree.c b/net/netfilter/nft_rbtree.c index 46214f2..417796f 100644 --- a/net/netfilter/nft_rbtree.c +++ b/net/netfilter/nft_rbtree.c @@ -37,10 +37,11 @@ static bool nft_rbtree_lookup(const struct nft_set *set, { const struct nft_rbtree *priv = nft_set_priv(set); const struct nft_rbtree_elem *rbe, *interval = NULL; - const struct rb_node *parent = priv->root.rb_node; + const struct rb_node *parent; int d; spin_lock_bh(&nft_rbtree_lock); + parent = priv->root.rb_node; while (parent != NULL) { rbe = rb_entry(parent, struct nft_rbtree_elem, node); @@ -158,7 +159,6 @@ static int nft_rbtree_get(const struct nft_set *set, struct nft_set_elem *elem) struct nft_rbtree_elem *rbe; int d; - spin_lock_bh(&nft_rbtree_lock); while (parent != NULL) { rbe = rb_entry(parent, struct nft_rbtree_elem, node); @@ -173,11 +173,9 @@ static int nft_rbtree_get(const struct nft_set *set, struct nft_set_elem *elem) !(rbe->flags & NFT_SET_ELEM_INTERVAL_END)) nft_data_copy(&elem->data, rbe->data); elem->flags = rbe->flags; - spin_unlock_bh(&nft_rbtree_lock); return 0; } } - spin_unlock_bh(&nft_rbtree_lock); return -ENOENT; } @@ -190,7 +188,6 @@ static void nft_rbtree_walk(const struct nft_ctx *ctx, struct nft_set_elem elem; struct rb_node *node; - spin_lock_bh(&nft_rbtree_lock); for (node = rb_first(&priv->root); node != NULL; node = rb_next(node)) { if (iter->count < iter->skip) goto cont; @@ -203,14 +200,11 @@ static void nft_rbtree_walk(const struct nft_ctx *ctx, elem.flags = rbe->flags; iter->err = iter->fn(ctx, set, iter, &elem); - if (iter->err < 0) { - spin_unlock_bh(&nft_rbtree_lock); + if (iter->err < 0) return; - } cont: iter->count++; } - spin_unlock_bh(&nft_rbtree_lock); } static unsigned int nft_rbtree_privsize(const struct nlattr * const nla[])
Fix a race condition and unnecessary locking: * the root rb_node must only be accessed under the lock in nft_rbtree_lookup() * the lock is not needed in lookup functions in netlink contexts Signed-off-by: Patrick McHardy <kaber@trash.net> --- net/netfilter/nft_rbtree.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-)