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Tue, 31 Mar 2026 23:13:48 -0700 (PDT) Received: from DESKTOP-MOQC9AF.mioffice.cn ([43.224.245.237]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35dbe668b24sm3692305a91.8.2026.03.31.23.13.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Mar 2026 23:13:47 -0700 (PDT) From: Zhan Xusheng X-Google-Original-From: Zhan Xusheng To: Gao Xiang Cc: linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org, Zhan Xusheng Subject: [PATCH] erofs: include the trailing NUL in FS_IOC_GETFSLABEL Date: Wed, 1 Apr 2026 14:13:42 +0800 Message-ID: <20260401061342.40166-1-zhanxusheng@xiaomi.com> X-Mailer: git-send-email 2.43.0 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" erofs_ioctl_get_volume_label() passes strlen(sbi->volume_name) as the length to copy_to_user(), which copies the label string without the trailing NUL byte. Since FS_IOC_GETFSLABEL callers expect a NUL-terminated string in the FSLABEL_MAX-sized buffer and may not pre-zero the buffer, this can cause userspace to read past the label into uninitialised stack memory. Fix this by using strlen() + 1 to include the NUL terminator, consistent with how ext4 and xfs implement FS_IOC_GETFSLABEL. Signed-off-by: Zhan Xusheng Reviewed-by: Gao Xiang --- fs/erofs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c index 4b3d21402e10..a188c570087a 100644 --- a/fs/erofs/inode.c +++ b/fs/erofs/inode.c @@ -351,7 +351,7 @@ static int erofs_ioctl_get_volume_label(struct inode *i= node, void __user *arg) ret =3D clear_user(arg, 1); else ret =3D copy_to_user(arg, sbi->volume_name, - strlen(sbi->volume_name)); + strlen(sbi->volume_name) + 1); return ret ? -EFAULT : 0; } =20 --=20 2.43.0