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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Paul M Stillwell Jr , Rasesh Mody , Sudarsana Kalluru , GR-Linux-NIC-Dev@marvell.com, Krishna Gudipati , Anil Gurumurthy , Sudarsana Kalluru , "James E.J. Bottomley" , "Martin K. Petersen" , Fabian Frederick , Saurav Kashyap , Javed Hasan , GR-QLogic-Storage-Upstream@marvell.com, Nilesh Javali , Arun Easi , Manish Rangankar , Vineeth Vijayan , Peter Oberparleiter , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Saurav Kashyap , linux-s390@vger.kernel.org, Jens Axboe Subject: Re: [PATCH 5/5] drivers/s390/cio: ensure the copied buf is NULL terminated Message-ID: <20240423065052.10211-C-hca@linux.ibm.com> References: <20240422-fix-oob-read-v1-0-e02854c30174@gmail.com> <20240422-fix-oob-read-v1-5-e02854c30174@gmail.com> Precedence: bulk X-Mailing-List: linux-scsi@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: <20240422-fix-oob-read-v1-5-e02854c30174@gmail.com> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: JfbWZJYjgQ-6sEoUNR3sO4YsC4Gb-N7m X-Proofpoint-ORIG-GUID: dN-FvMKmlspL8yk4i7YrijWq2YdDYnU8 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-04-23_04,2024-04-22_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 suspectscore=0 priorityscore=1501 mlxscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 phishscore=0 mlxlogscore=965 bulkscore=0 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2404010000 definitions=main-2404230019 On Mon, Apr 22, 2024 at 11:41:40PM +0700, Bui Quang Minh wrote: > Currently, we allocate a lbuf-sized kernel buffer and copy lbuf from > userspace to that buffer. Later, we use scanf on this buffer but we don't > ensure that the string is terminated inside the buffer, this can lead to > OOB read when using scanf. Fix this issue by allocating 1 more byte to at > the end of buffer and write NULL terminator to the end of buffer after > userspace copying. > > Fixes: a4f17cc72671 ("s390/cio: add CRW inject functionality") > Signed-off-by: Bui Quang Minh > --- > drivers/s390/cio/cio_inject.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/s390/cio/cio_inject.c b/drivers/s390/cio/cio_inject.c > index 8613fa937237..9b69fbf49f60 100644 > --- a/drivers/s390/cio/cio_inject.c > +++ b/drivers/s390/cio/cio_inject.c > @@ -95,10 +95,11 @@ static ssize_t crw_inject_write(struct file *file, const char __user *buf, > return -EINVAL; > } > > - buffer = vmemdup_user(buf, lbuf); > + buffer = vmemdup_user(buf, lbuf + 1); > if (IS_ERR(buffer)) > return -ENOMEM; > > + buffer[lbuf] = '\0'; This would read one byte too much from user space, and could potentially fault. Why isn't this simply memdup_user_nul() like all others, which would do the right thing?