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Fri, 12 Sep 2025 09:56:22 +0000 (GMT) Date: Fri, 12 Sep 2025 11:56:20 +0200 From: Heiko Carstens To: Thorsten Blum Cc: Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] s390/hypfs_sprp: Replace kzalloc() + copy_from_user() with memdup_user() Message-ID: <20250912095620.10147A01-hca@linux.ibm.com> References: <20250911214539.1483234-2-thorsten.blum@linux.dev> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250911214539.1483234-2-thorsten.blum@linux.dev> X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: QDMmIkRIwvAalAgv7o5FG_OXx888oGZB X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTA2MDIzNSBTYWx0ZWRfXwczV/wDCeKOE 9JgtG9TJkZap/9lK7e6mi2gL6wCKmXJu3m2EL7ZGGUJcV/KozgPZJHQQ+h4d2Dehb0mb/s0Erie SYYn5Zg2PHPWaHRy67nG2b2kSXmnoTk+2RPUxz6HRreouRnOtURrn2oQgJ65iorjTbQg9M1aMj3 xfcajPxVXx51XKTIr5XgrMhTp20njD+847nDwj7fJNgIFXwyViNcTZKoWwHNsGsQLfGy/MNf8lz 4oI/NCvZkNla8Tb3GWx4jx/yZqWVYMGiDQqkov2cO8yY0g5NDxFg9p5Qle8eUfg19/4s6shrPvS RoLbc+jsXjXVQO81GAMv/3QE4PEkdGVCRghV7irG1VeJxmMLJYyps1MeeVbOC2El53/mg2sOwXp ssWrvJTl X-Proofpoint-GUID: QDMmIkRIwvAalAgv7o5FG_OXx888oGZB X-Authority-Analysis: v=2.4 cv=F59XdrhN c=1 sm=1 tr=0 ts=68c3ee4b cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=kj9zAlcOel0A:10 a=yJojWOMRYYMA:10 a=-POyQxMZsFGaTXn31B0A:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-12_03,2025-09-11_02,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 clxscore=1015 impostorscore=0 bulkscore=0 adultscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2509060235 On Thu, Sep 11, 2025 at 11:45:38PM +0200, Thorsten Blum wrote: > Replace kzalloc() followed by copy_from_user() with memdup_user() to > improve and simplify __hypfs_sprp_ioctl(). > > Return early if an error occurs instead of trying to allocate memory for > 'diag304' when memory allocation for 'data' already failed. > > No functional changes intended. > > Signed-off-by: Thorsten Blum > --- > arch/s390/hypfs/hypfs_sprp.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/arch/s390/hypfs/hypfs_sprp.c b/arch/s390/hypfs/hypfs_sprp.c > index 9fc3f0dae8f0..be11634bc7db 100644 > --- a/arch/s390/hypfs/hypfs_sprp.c > +++ b/arch/s390/hypfs/hypfs_sprp.c > @@ -73,15 +73,16 @@ static int __hypfs_sprp_ioctl(void __user *user_area) > void *data; > int rc; > > - rc = -ENOMEM; > data = (void *)get_zeroed_page(GFP_KERNEL); > - diag304 = kzalloc(sizeof(*diag304), GFP_KERNEL); > - if (!data || !diag304) > - goto out; > + if (!data) > + return -ENOMEM; > > - rc = -EFAULT; > - if (copy_from_user(diag304, user_area, sizeof(*diag304))) > + diag304 = memdup_user(user_area, sizeof(*diag304)); > + if (IS_ERR(diag304)) { > + rc = PTR_ERR(diag304); > goto out; > + } This is not an improvement and also incorrect, since kfree() may now be called with an error pointer. Please don't send patches like this which aren't a real improvement. This is just pointless code churn, and a waste of time.