From: Thorsten Blum <thorsten.blum@linux.dev>
To: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] s390/hypfs_sprp: Replace kzalloc() + copy_from_user() with memdup_user()
Date: Fri, 12 Sep 2025 12:51:05 +0200 [thread overview]
Message-ID: <25EFA2E0-5119-400F-A787-D2BDB78B8BE0@linux.dev> (raw)
In-Reply-To: <D56B6A09-8633-402D-A942-1C24AE465AC8@linux.dev>
On 12. Sep 2025, at 12:09, Thorsten Blum wrote:
> On 12. Sep 2025, at 11:56, Heiko Carstens wrote:
>> This is not an improvement and also incorrect, since kfree() may now
>> be called with an error pointer.
>
> Unless I'm missing something, kfree() works just fine with error
> pointers. See linux/slab.h:
>
> DEFINE_FREE(kfree, void *, if (!IS_ERR_OR_NULL(_T)) kfree(_T))
And unless kzalloc() is required here, memdup_user() is an improvement,
since it uses kmalloc() internally and avoids unnecessarily zeroing the
memory before overwriting it with copy_from_user().
Thanks,
Thorsten
next prev parent reply other threads:[~2025-09-12 10:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-11 21:45 [PATCH] s390/hypfs_sprp: Replace kzalloc() + copy_from_user() with memdup_user() Thorsten Blum
2025-09-12 9:56 ` Heiko Carstens
2025-09-12 10:09 ` Thorsten Blum
2025-09-12 10:51 ` Thorsten Blum [this message]
2025-09-12 11:10 ` Heiko Carstens
2025-09-12 11:06 ` Heiko Carstens
2025-09-12 12:50 ` Thorsten Blum
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