From: Heiko Carstens <hca@linux.ibm.com>
To: Thorsten Blum <thorsten.blum@linux.dev>
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 13:10:46 +0200 [thread overview]
Message-ID: <20250912111046.10147D2d-hca@linux.ibm.com> (raw)
In-Reply-To: <25EFA2E0-5119-400F-A787-D2BDB78B8BE0@linux.dev>
On Fri, Sep 12, 2025 at 12:51:05PM +0200, Thorsten Blum wrote:
> 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().
Again, there are gazillions of similar trivial cleanup patches possible. The
additional zeroing in this case doesn't matter at all, since this code is
executed once a year.
Reviewing and integrating such patches could keep us busy all day long.
So, please don't send such patches.
Patches which fix (potential) bugs are welcome however.
next prev parent reply other threads:[~2025-09-12 11:10 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
2025-09-12 11:10 ` Heiko Carstens [this message]
2025-09-12 11:06 ` Heiko Carstens
2025-09-12 12:50 ` Thorsten Blum
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