* [PATCH nf] netfilter: nf_queue: don't assume sk is full socket
@ 2022-02-23 20:10 Florian Westphal
2022-02-24 14:58 ` Pablo Neira Ayuso
2022-02-25 11:58 ` Oleksandr Natalenko
0 siblings, 2 replies; 3+ messages in thread
From: Florian Westphal @ 2022-02-23 20:10 UTC (permalink / raw)
To: netfilter-devel; +Cc: Florian Westphal
There is no guarantee that state->sk refers to a full socket.
If refcount transitions to 0, sock_put calls sk_free which then ends up
with garbage fields.
I'd like to thank Oleksandr Natalenko and Jiri Benc for considerable
debug work and pointing out state->sk oddities.
Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
No reproducer, so there is a chance that the reported crash is caused by
something else. That said, I don't see how sock_put use is safe here.
net/netfilter/nf_queue.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index 6d12afabfe8a..178742a110d9 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -54,7 +54,7 @@ static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
dev_put(state->in);
dev_put(state->out);
if (state->sk)
- sock_put(state->sk);
+ sock_gen_put(state->sk);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
dev_put(entry->physin);
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH nf] netfilter: nf_queue: don't assume sk is full socket
2022-02-23 20:10 [PATCH nf] netfilter: nf_queue: don't assume sk is full socket Florian Westphal
@ 2022-02-24 14:58 ` Pablo Neira Ayuso
2022-02-25 11:58 ` Oleksandr Natalenko
1 sibling, 0 replies; 3+ messages in thread
From: Pablo Neira Ayuso @ 2022-02-24 14:58 UTC (permalink / raw)
To: Florian Westphal; +Cc: netfilter-devel
On Wed, Feb 23, 2022 at 09:10:04PM +0100, Florian Westphal wrote:
> There is no guarantee that state->sk refers to a full socket.
>
> If refcount transitions to 0, sock_put calls sk_free which then ends up
> with garbage fields.
>
> I'd like to thank Oleksandr Natalenko and Jiri Benc for considerable
> debug work and pointing out state->sk oddities.
Applied, thanks
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH nf] netfilter: nf_queue: don't assume sk is full socket
2022-02-23 20:10 [PATCH nf] netfilter: nf_queue: don't assume sk is full socket Florian Westphal
2022-02-24 14:58 ` Pablo Neira Ayuso
@ 2022-02-25 11:58 ` Oleksandr Natalenko
1 sibling, 0 replies; 3+ messages in thread
From: Oleksandr Natalenko @ 2022-02-25 11:58 UTC (permalink / raw)
To: netfilter-devel; +Cc: Florian Westphal
Hello.
On středa 23. února 2022 21:10:04 CET Florian Westphal wrote:
> There is no guarantee that state->sk refers to a full socket.
>
> If refcount transitions to 0, sock_put calls sk_free which then ends up
> with garbage fields.
>
> I'd like to thank Oleksandr Natalenko and Jiri Benc for considerable
> debug work and pointing out state->sk oddities.
No thank you for spotting the exact issue.
> Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
> Signed-off-by: Florian Westphal <fw@strlen.de>
Tested-by: Oleksandr Natalenko <oleksandr@redhat.com>
> ---
> No reproducer, so there is a chance that the reported crash is caused by
> something else. That said, I don't see how sock_put use is safe here.
Using your reproducer from [1] I could trigger the issue on unpatched kernel and couldn't trigger the issue on patched kernel with the patch from below applied.
[1] https://patchwork.ozlabs.org/project/netfilter-devel/patch/20220224152118.20619-1-fw@strlen.de/
>
> net/netfilter/nf_queue.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
> index 6d12afabfe8a..178742a110d9 100644
> --- a/net/netfilter/nf_queue.c
> +++ b/net/netfilter/nf_queue.c
> @@ -54,7 +54,7 @@ static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
> dev_put(state->in);
> dev_put(state->out);
> if (state->sk)
> - sock_put(state->sk);
> + sock_gen_put(state->sk);
>
> #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
> dev_put(entry->physin);
>
--
Oleksandr Natalenko (post-factum)
Principal Software Maintenance Engineer
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-02-23 20:10 [PATCH nf] netfilter: nf_queue: don't assume sk is full socket Florian Westphal
2022-02-24 14:58 ` Pablo Neira Ayuso
2022-02-25 11:58 ` Oleksandr Natalenko
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