Re: [PATCH 6.4 118/800] net/handshake: Unpin sock->file if a handshake is cancelled

Chuck Lever III
2023-07-17T19:06:48Z

> On Jul 17, 2023, at 2:53 PM, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
>
> On Mon, Jul 17, 2023 at 05:55:46PM +0000, Chuck Lever III wrote:
>>
>>
>>> On Jul 17, 2023, at 1:10 PM, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
>>>
>>> On Sun, Jul 16, 2023 at 08:43:58PM +0000, Chuck Lever III wrote:
>>>>
>>>>
>>>>> On Jul 16, 2023, at 3:39 PM, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
>>>>>
>>>>> From: Chuck Lever <chuck.lever@oracle.com>
>>>>>
>>>>> [ Upstream commit f921bd41001ccff2249f5f443f2917f7ef937daf ]
>>>>>
>>>>> If user space never calls DONE, sock->file's reference count remains
>>>>> elevated. Enable sock->file to be freed eventually in this case.
>>>>>
>>>>> Reported-by: Jakub Kacinski <kuba@kernel.org>
>>>>> Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
>>>>> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
>>>>> Signed-off-by: David S. Miller <davem@davemloft.net>
>>>>> Signed-off-by: Sasha Levin <sashal@kernel.org>
>>>>> ---
>>>>> net/handshake/handshake.h | 1 +
>>>>> net/handshake/request.c | 4 ++++
>>>>> 2 files changed, 5 insertions(+)
>>>>>
>>>>> diff --git a/net/handshake/handshake.h b/net/handshake/handshake.h
>>>>> index 4dac965c99df0..8aeaadca844fd 100644
>>>>> --- a/net/handshake/handshake.h
>>>>> +++ b/net/handshake/handshake.h
>>>>> @@ -31,6 +31,7 @@ struct handshake_req {
>>>>> struct list_head hr_list;
>>>>> struct rhash_head hr_rhash;
>>>>> unsigned long hr_flags;
>>>>> + struct file *hr_file;
>>>>> const struct handshake_proto *hr_proto;
>>>>> struct sock *hr_sk;
>>>>> void (*hr_odestruct)(struct sock *sk);
>>>>> diff --git a/net/handshake/request.c b/net/handshake/request.c
>>>>> index 94d5cef3e048b..d78d41abb3d99 100644
>>>>> --- a/net/handshake/request.c
>>>>> +++ b/net/handshake/request.c
>>>>> @@ -239,6 +239,7 @@ int handshake_req_submit(struct socket *sock, struct handshake_req *req,
>>>>> }
>>>>> req->hr_odestruct = req->hr_sk->sk_destruct;
>>>>> req->hr_sk->sk_destruct = handshake_sk_destruct;
>>>>> + req->hr_file = sock->file;
>>>>>
>>>>> ret = -EOPNOTSUPP;
>>>>> net = sock_net(req->hr_sk);
>>>>> @@ -334,6 +335,9 @@ bool handshake_req_cancel(struct sock *sk)
>>>>> return false;
>>>>> }
>>>>>
>>>>> + /* Request accepted and waiting for DONE */
>>>>> + fput(req->hr_file);
>>>>> +
>>>>> out_true:
>>>>> trace_handshake_cancel(net, req, sk);
>>>>>
>>>>> --
>>>>> 2.39.2
>>>>>
>>>>>
>>>>>
>>>>
>>>> Don't take this one. It's fixed by a later commit:
>>>>
>>>> 361b6889ae636926cdff517add240c3c8e24593a
>>>>
>>>> that reverts it.
>>>
>>> How? That commit is in 6.4 already, yet this commit, is from 6.5-rc1.
>>
>> I do not see f921bd41001ccff2249f5f443f2917f7ef937daf in v6.5-rc2.
>> Whatever that is, it's not in upstream.
>
> I see it:
> $ git describe --contains f921bd41001ccff2249f5f443f2917f7ef937daf
> v6.5-rc1~163^2~292^2~1
> $ git show --oneline f921bd41001ccff2249f5f443f2917f7ef937daf | head -n 1
> f921bd41001c net/handshake: Unpin sock->file if a handshake is cancelled

Yes, I see it too, it's in the repo. But it's not in the commit
history of tag v6.5-rc2, and the source tree, as of v6.5-rc2,
does not have that change.

> $ git describe --contains 361b6889ae636926cdff517add240c3c8e24593a
> v6.4-rc7~17^2~14
> $ git show --oneline 361b6889ae636926cdff517add240c3c8e24593a | head -n 1
> 361b6889ae63 net/handshake: remove fput() that causes use-after-free
>
> So commit 361b6889ae63 ("net/handshake: remove fput() that causes
> use-after-free") came into 6.4-rc7, and commit f921bd41001c
> ("net/handshake: Unpin sock->file if a handshake is cancelled") came
> into 6.5-rc1.

f921bd41001c isn't in 6.5-rc at all, according to the commit history.

>> [cel@manet server-development]$ git log --pretty=oneline v6.5-rc2 -- net/handshake/
>> 173780ff18a93298ca84224cc79df69f9cc198ce Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
>> 361b6889ae636926cdff517add240c3c8e24593a net/handshake: remove fput() that causes use-after-free
>> 9b66ee06e5ca2698d0ba12a7ad7188cb724279e7 net: ynl: prefix uAPI header include with uapi/
>> 26fb5480a27d34975cc2b680b77af189620dd740 net/handshake: Enable the SNI extension to work properly
>> 1ce77c998f0415d7d9d91cb9bd7665e25c8f75f1 net/handshake: Unpin sock->file if a handshake is cancelled
>> fc490880e39d86c65ab2bcbd357af1950fa55e48 net/handshake: handshake_genl_notify() shouldn't ignore @flags
>> 7afc6d0a107ffbd448c96eb2458b9e64a5af7860 net/handshake: Fix uninitialized local variable
>> 7ea9c1ec66bc099b0bfba961a8a46dfe25d7d8e4 net/handshake: Fix handshake_dup() ref counting
>> a095326e2c0f33743ce8e887d5b90edf3f36cced net/handshake: Remove unneeded check from handshake_dup()
>> 18c40a1cc1d990c51381ef48cd93fdb31d5cd903 net/handshake: Fix sock->file allocation
>> b21c7ba6d9a5532add3827a3b49f49cbc0cb9779 net/handshake: Squelch allocation warning during Kunit test
>> 6aa445e39693bff9c98b12f960e66b4e18c7378b net/handshake: Fix section mismatch in handshake_exit
>> 88232ec1ec5ecf4aa5de439cff3d5e2b7adcac93 net/handshake: Add Kunit tests for the handshake consumer API
>> 2fd5532044a89d2403b543520b4902e196f7d165 net/handshake: Add a kernel API for requesting a TLSv1.3 handshake
>> 3b3009ea8abb713b022d94fba95ec270cf6e7eae net/handshake: Create a NETLINK service for handling handshake requests
>> [cel@manet server-development]$
>>
>> But I do see 1ce77c998f0415d7d9d91cb9bd7665e25c8f75f1 and the
>> commit that reverts it, 361b6889ae636926cdff517add240c3c8e24593a.
>
> Very strange. As this is confusing, I'll just drop it for now until
> someone can straighten it out :)

Thanks for dropping!

--
Chuck Lever