linux-kernel - Re: [PATCH] padata: do not leak refcount in reorder

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Message-ID: <jmo6jjku7t4ftutfycp5zxpy7fhdvbprrkjpl6rijdwdz4z5xx@fzqjm5o2heol>
Date: Tue, 20 May 2025 12:00:12 -0400
From: Daniel Jordan <daniel.m.jordan@...cle.com>
To: Dominik Grzegorzek <dominik.grzegorzek@...cle.com>
Cc: Steffen Klassert <steffen.klassert@...unet.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Chen Ridong <chenridong@...wei.com>,
        "open list:PADATA PARALLEL EXECUTION MECHANISM" <linux-crypto@...r.kernel.org>,
        "open list:PADATA PARALLEL EXECUTION MECHANISM" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] padata: do not leak refcount in reorder_work

On Sun, May 18, 2025 at 07:45:31PM +0200, Dominik Grzegorzek wrote:
> A recent patch that addressed a UAF introduced a reference count leak:
> the parallel_data refcount is incremented unconditionally, regardless
> of the return value of queue_work(). If the work item is already queued,
> the incremented refcount is never decremented.
> 
> Fix this by checking the return value of queue_work() and decrementing
> the refcount when necessary.
> 
> Resolves:
> 
> Unreferenced object 0xffff9d9f421e3d80 (size 192):
>   comm "cryptomgr_probe", pid 157, jiffies 4294694003
>   hex dump (first 32 bytes):
>     80 8b cf 41 9f 9d ff ff b8 97 e0 89 ff ff ff ff  ...A............
>     d0 97 e0 89 ff ff ff ff 19 00 00 00 1f 88 23 00  ..............#.
>   backtrace (crc 838fb36):
>     __kmalloc_cache_noprof+0x284/0x320
>     padata_alloc_pd+0x20/0x1e0
>     padata_alloc_shell+0x3b/0xa0
>     0xffffffffc040a54d
>     cryptomgr_probe+0x43/0xc0
>     kthread+0xf6/0x1f0
>     ret_from_fork+0x2f/0x50
>     ret_from_fork_asm+0x1a/0x30
> 
> Fixes: dd7d37ccf6b1 ("padata: avoid UAF for reorder_work")
> Signed-off-by: Dominik Grzegorzek <dominik.grzegorzek@...cle.com>

I missed it too.  Thanks!

Acked-by: Daniel Jordan <daniel.m.jordan@...cle.com>