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Fri, 29 Aug 2025 01:30:22 -0700 (PDT) Received: from vickymqlin-1vvu545oca.codev-2.svc.cluster.local ([14.22.11.165]) by smtp.googlemail.com with ESMTPSA id 98e67ed59e1d1-3276fcf04b8sm7511108a91.26.2025.08.29.01.30.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Aug 2025 01:30:22 -0700 (PDT) From: Miaoqian Lin To: chris@zankel.net, jcmvbkbc@gmail.com, linmq006@gmail.com, thorsten.blum@linux.dev, viro@zeniv.linux.org.uk Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH] xtensa: simdisk: add input size check in proc_write_simdisk Date: Fri, 29 Aug 2025 16:30:15 +0800 Message-Id: <20250829083015.1992751-1-linmq006@gmail.com> X-Mailer: git-send-email 2.35.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" A malicious user could pass an arbitrarily bad value to memdup_user_nul(), potentially causing kernel crash. This follows the same pattern as commit ee76746387f6 ("netdevsim: prevent bad user input in nsim_dev_health_break_write()") Fixes: b6c7e873daf7 ("xtensa: ISS: add host file-based simulated disk") Fixes: 16e5c1fc3604 ("convert a bunch of open-coded instances of memdup_use= r_nul()") Cc: stable@vger.kernel.org Signed-off-by: Miaoqian Lin --- arch/xtensa/platforms/iss/simdisk.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/xtensa/platforms/iss/simdisk.c b/arch/xtensa/platforms/is= s/simdisk.c index 6ed009318d24..3cafc8feddee 100644 --- a/arch/xtensa/platforms/iss/simdisk.c +++ b/arch/xtensa/platforms/iss/simdisk.c @@ -231,10 +231,14 @@ static ssize_t proc_read_simdisk(struct file *file, c= har __user *buf, static ssize_t proc_write_simdisk(struct file *file, const char __user *bu= f, size_t count, loff_t *ppos) { - char *tmp =3D memdup_user_nul(buf, count); + char *tmp; struct simdisk *dev =3D pde_data(file_inode(file)); int err; =20 + if (count =3D=3D 0 || count > PAGE_SIZE) + return -EINVAL; + + tmp =3D memdup_user_nul(buf, count); if (IS_ERR(tmp)) return PTR_ERR(tmp); =20 --=20 2.35.1