6.6-stable review patch. If anyone has any objections, please let me know.
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From: Charalampos Mitrodimas charmitro@posteo.net
[ Upstream commit f29ccaa07cf3d35990f4d25028cc55470d29372b ]
syzbot reported a refcount warning [1] caused by calling get_net() on a network namespace that is being destroyed (refcount=0). This happens when a TIPC discovery timer fires during network namespace cleanup.
The recently added get_net() call in commit e279024617134 ("net/tipc: fix slab-use-after-free Read in tipc_aead_encrypt_done") attempts to hold a reference to the network namespace. However, if the namespace is already being destroyed, its refcount might be zero, leading to the use-after-free warning.
Replace get_net() with maybe_get_net(), which safely checks if the refcount is non-zero before incrementing it. If the namespace is being destroyed, return -ENODEV early, after releasing the bearer reference.
[1]: https://lore.kernel.org/all/68342b55.a70a0220.253bc2.0091.GAE@google.com/T/#...
Reported-by: syzbot+f0c4a4aba757549ae26c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68342b55.a70a0220.253bc2.0091.GAE@google.com/T/#... Fixes: e27902461713 ("net/tipc: fix slab-use-after-free Read in tipc_aead_encrypt_done") Signed-off-by: Charalampos Mitrodimas charmitro@posteo.net Reviewed-by: Tung Nguyen tung.quang.nguyen@est.tech Link: https://patch.msgid.link/20250527-net-tipc-warning-v2-1-df3dc398a047@posteo.... Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/tipc/crypto.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c index 8584893b47851..79f91b6ca8c84 100644 --- a/net/tipc/crypto.c +++ b/net/tipc/crypto.c @@ -818,7 +818,11 @@ static int tipc_aead_encrypt(struct tipc_aead *aead, struct sk_buff *skb, }
/* Get net to avoid freed tipc_crypto when delete namespace */ - get_net(aead->crypto->net); + if (!maybe_get_net(aead->crypto->net)) { + tipc_bearer_put(b); + rc = -ENODEV; + goto exit; + }
/* Now, do encrypt */ rc = crypto_aead_encrypt(req);