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Tue, 24 Oct 2023 16:31:05 +0000 (GMT) Message-ID: Date: Tue, 24 Oct 2023 18:31:05 +0200 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] s390/qeth: replace deprecated strncpy with strscpy To: Justin Stitt , Alexandra Winter , Wenjia Zhang , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle Cc: linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org References: <20231023-strncpy-drivers-s390-net-qeth_core_main-c-v1-1-e7ce65454446@google.com> Content-Language: en-GB From: Thorsten Winkler In-Reply-To: <20231023-strncpy-drivers-s390-net-qeth_core_main-c-v1-1-e7ce65454446@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-GUID: BwEG0FpVjPOs9G4YuxgdOSKf9jDJn1ZN X-Proofpoint-ORIG-GUID: XAQV7EPJWV3xI0saw8O4bh3S0Kz7Cesg Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.980,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-10-24_16,2023-10-24_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1015 phishscore=0 mlxlogscore=999 priorityscore=1501 mlxscore=0 adultscore=0 malwarescore=0 suspectscore=0 lowpriorityscore=0 spamscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2310170001 definitions=main-2310240143 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 23.10.23 21:39, Justin Stitt wrote: > strncpy() is deprecated for use on NUL-terminated destination strings > [1] and as such we should prefer more robust and less ambiguous string > interfaces. > > We expect new_entry->dbf_name to be NUL-terminated based on its use with > strcmp(): > | if (strcmp(entry->dbf_name, name) == 0) { > > Moreover, NUL-padding is not required as new_entry is kzalloc'd just > before this assignment: > | new_entry = kzalloc(sizeof(struct qeth_dbf_entry), GFP_KERNEL); > > ... rendering any future NUL-byte assignments (like the ones strncpy() > does) redundant. > > Considering the above, a suitable replacement is `strscpy` [2] due to > the fact that it guarantees NUL-termination on the destination buffer > without unnecessarily NUL-padding. > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] > Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] > Link: https://github.com/KSPP/linux/issues/90 > Cc: linux-hardening@vger.kernel.org > Signed-off-by: Justin Stitt LGTM, thank you! Reviewed-by: Thorsten Winkler Tested-by: Thorsten Winkler > --- > Note: build-tested only. > > Found with: $ rg "strncpy\(" > --- > drivers/s390/net/qeth_core_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c > index cd783290bde5..6af2511e070c 100644 > --- a/drivers/s390/net/qeth_core_main.c > +++ b/drivers/s390/net/qeth_core_main.c > @@ -6226,7 +6226,7 @@ static int qeth_add_dbf_entry(struct qeth_card *card, char *name) > new_entry = kzalloc(sizeof(struct qeth_dbf_entry), GFP_KERNEL); > if (!new_entry) > goto err_dbg; > - strncpy(new_entry->dbf_name, name, DBF_NAME_LEN); > + strscpy(new_entry->dbf_name, name, sizeof(new_entry->dbf_name)); > new_entry->dbf_info = card->debug; > mutex_lock(&qeth_dbf_list_mutex); > list_add(&new_entry->dbf_list, &qeth_dbf_list); > > --- > base-commit: 9c5d00cb7b6bbc5a7965d9ab7d223b5402d1f02c > change-id: 20231023-strncpy-drivers-s390-net-qeth_core_main-c-0b0ee08672ec > > Best regards, > -- > Justin Stitt > >