Re: [PATCH] tipc: Fix potential tipc_aead refcnt leak in tipc_crypto_rcv

[David Miller]

From: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Date: Wed, 15 Apr 2020 16:39:56 +0800

> tipc_crypto_rcv() invokes tipc_aead_get(), which returns a reference of
> the tipc_aead object to "aead" with increased refcnt.
> 
> When tipc_crypto_rcv() returns, the original local reference of "aead"
> becomes invalid, so the refcount should be decreased to keep refcount
> balanced.
> 
> The issue happens in one error path of tipc_crypto_rcv(). When TIPC
> message decryption status is EINPROGRESS or EBUSY, the function forgets
> to decrease the refcnt increased by tipc_aead_get() and causes a refcnt
> leak.
> 
> Fix this issue by calling tipc_aead_put() on the error path when TIPC
> message decryption status is EINPROGRESS or EBUSY.
> 
> Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
> Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>

Applied and queued up for -stable.

This code is harder to audit than it needs to be due to the special
casing of things like -ENOKEY etc.  It should rather explicitly handle
the NULL test on aead in this top-level piece of code, which would
make the validation of aead reference counting much more explicit and
clear.