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authorAntoine Tenart <atenart@kernel.org>2022-02-07 18:13:18 +0100
committerDavid S. Miller <davem@davemloft.net>2022-02-09 11:41:47 +0000
commitcfc56f85e72f5b9c5c5be26dc2b16518d36a7868 (patch)
tree7ee7ee08b6f3cad5d33d3861cf80810613cb1955 /include
parent7db788ad627aabff2b74d4f1a3b68516d0fee0d7 (diff)
net: do not keep the dst cache when uncloning an skb dst and its metadata
When uncloning an skb dst and its associated metadata a new dst+metadata is allocated and the tunnel information from the old metadata is copied over there. The issue is the tunnel metadata has references to cached dst, which are copied along the way. When a dst+metadata refcount drops to 0 the metadata is freed including the cached dst entries. As they are also referenced in the initial dst+metadata, this ends up in UaFs. In practice the above did not happen because of another issue, the dst+metadata was never freed because its refcount never dropped to 0 (this will be fixed in a subsequent patch). Fix this by initializing the dst cache after copying the tunnel information from the old metadata to also unshare the dst cache. Fixes: d71785ffc7e7 ("net: add dst_cache to ovs vxlan lwtunnel") Cc: Paolo Abeni <pabeni@redhat.com> Reported-by: Vlad Buslov <vladbu@nvidia.com> Tested-by: Vlad Buslov <vladbu@nvidia.com> Signed-off-by: Antoine Tenart <atenart@kernel.org> Acked-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/net/dst_metadata.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/net/dst_metadata.h b/include/net/dst_metadata.h
index 14efa0ded75d..b997e0c1e362 100644
--- a/include/net/dst_metadata.h
+++ b/include/net/dst_metadata.h
@@ -123,6 +123,19 @@ static inline struct metadata_dst *tun_dst_unclone(struct sk_buff *skb)
memcpy(&new_md->u.tun_info, &md_dst->u.tun_info,
sizeof(struct ip_tunnel_info) + md_size);
+#ifdef CONFIG_DST_CACHE
+ /* Unclone the dst cache if there is one */
+ if (new_md->u.tun_info.dst_cache.cache) {
+ int ret;
+
+ ret = dst_cache_init(&new_md->u.tun_info.dst_cache, GFP_ATOMIC);
+ if (ret) {
+ metadata_dst_free(new_md);
+ return ERR_PTR(ret);
+ }
+ }
+#endif
+
skb_dst_drop(skb);
dst_hold(&new_md->dst);
skb_dst_set(skb, &new_md->dst);