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net: fix a memleak when uncloning an skb dst and its metadata

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[ Upstream commit 9eeabdf17f ]

When uncloning an skb dst and its associated metadata, a new
dst+metadata is allocated and later replaces the old one in the skb.
This is helpful to have a non-shared dst+metadata attached to a specific
skb.

The issue is the uncloned dst+metadata is initialized with a refcount of
1, which is increased to 2 before attaching it to the skb. When
tun_dst_unclone returns, the dst+metadata is only referenced from a
single place (the skb) while its refcount is 2. Its refcount will never
drop to 0 (when the skb is consumed), leading to a memory leak.

Fix this by removing the call to dst_hold in tun_dst_unclone, as the
dst+metadata refcount is already 1.

Fixes: fc4099f172 ("openvswitch: Fix egress tunnel info.")
Cc: Pravin B Shelar <pshelar@ovn.org>
Reported-by: Vlad Buslov <vladbu@nvidia.com>
Tested-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Antoine Tenart 2022-02-07 18:13:19 +01:00 committed by Greg Kroah-Hartman
parent 2e9fd2d0f6
commit 00e6d6c3bc
1 changed files with 0 additions and 1 deletions
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1
include/net/dst_metadata.h
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@ -137,7 +137,6 @@ static inline struct metadata_dst *tun_dst_unclone(struct sk_buff *skb)
#endif #endif
skb_dst_drop(skb); skb_dst_drop(skb);
dst_hold(&new_md->dst);
skb_dst_set(skb, &new_md->dst); skb_dst_set(skb, &new_md->dst);
return new_md; return new_md;
} }