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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="Xc/lpKFD"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D52C1607264F; Wed, 4 Nov 2026 19:20:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Xc/lpKFD Received: by smtp.kernel.org (Postfix) with ESMTPSA id E53051F00919; Wed, 4 Nov 2026 19:20:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793820021; bh=bDYBcNUn+VWuCpTwTZF6KvGO9475Dcj2RU9o+tvUNt0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Xc/lpKFDn4s3PLh92W7MP/0EYRbr9DtSlo+aTgCoiS4rp456CG2OTm4mdzAcBJWEq Ldjk5qAoEyhPyjStEGoJwwsLF6muQudRMZSm3dpoh/6WOOqikDwAONtjMuVpHReos4 Y67yz+y4bnZfnPjGe5X72XzUWZlpcgaEPlqDhTQSTzjJGylhHoAXVkmsvgtRloeENx Ezkm9787vd7BxlmMILJww46DT1dWDqRcMPOg2nMKQMVCbPmPG41MkkecEf01xpeInf S+AV+2Ll9y4McQGjdLnxElbFeubshKJGcRNGF7y6UPi9zZBWMvJNlUtStZmpr1zHH6 a4kGFVBEfnA0w== From: Christian Brauner To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Jann Horn , Josef Bacik , Chris Mason , Jeff Layton , NeilBrown , Eric Dumazet , Thomas Gleixner , Al Viro , Jonathan Corbet , Christoph Hellwig , Greg Kroah-Hartman , Joel Granados , Kees Cook , Jan Kara , Jan Kara , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-um@lists.infradead.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, ntfs3@lists.linux.dev, platform-driver-x86@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, netfilter-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, ibm-acpi-devel@lists.sourceforge.net, jfs-discussion@lists.sourceforge.net, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, linux-atm-general@lists.sourceforge.net, Takashi Iwai , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, linux-debuggers@vger.kernel.org, "Christian Brauner (Amutable)" , Chuck Lever , stable@vger.kernel.org Subject: [PATCH RESEND v2 17/51] s390/dasd: don't look in front of the buffer on an empty write Date: Wed, 4 Nov 2026 20:20:07 +0100 Message-ID: <20261104-work-procfs-bugfixes-v2-17-021c84d852e0@kernel.org> In-Reply-To: <20261104-work-procfs-bugfixes-v2-0-021c84d852e0@kernel.org> References: <20261104-work-procfs-bugfixes-v2-0-021c84d852e0@kernel.org> X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=952; i=brauner@kernel.org; h=from:subject:message-id; bh=vNxDJDpmoyfXJahneUuQ9vEH9eL70g/8w71rNTJgUxc=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9bnywlMF3yW3bTMV5otIz0k5cNnaUnbRb6akLs2LWJ ybd53uyOkpZGMS4GGTFFFkc2k3C5ZbzVGw2ytSAmcPKBDKEgYtTACYyczUjw+J7+6Q6zp3ZqLzq nmj5ZNvI96xHteJ17jyP5eFsniikWcrIcPHN7+NqVe8Wda9KbvPRPx9rN23XpqQDn9ky+1XSGSp leAE= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: 8bit dasd_get_user_string() strips a trailing newline by looking at the last byte that was written. For an empty write that's the byte in front of the buffer it just allocated. Only look if something was written. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner (Amutable) --- drivers/s390/block/dasd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c index 2ffe404b890f..e97891e58957 100644 --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -933,7 +933,7 @@ char *dasd_get_user_string(const char __user *user_buf, size_t user_len) return ERR_PTR(-EFAULT); } /* got the string, now strip linefeed. */ - if (buffer[user_len - 1] == '\n') + if (user_len && buffer[user_len - 1] == '\n') buffer[user_len - 1] = 0; else buffer[user_len] = 0; -- 2.53.0