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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=L4z066t7; 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 87006606D80F; Wed, 4 Nov 2026 17:49:22 +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=L4z066t7 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11ADA1F000C1; Wed, 4 Nov 2026 17:49:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793814562; bh=bDYBcNUn+VWuCpTwTZF6KvGO9475Dcj2RU9o+tvUNt0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=L4z066t7qk8SNBZ3qr8F1Dv4FM+zeL5UMqbVPpZhgdQRsqgneSAYM0s8mSty+AN6F uOpJwVDXNMcIMJN/l4FNHGQgvK/QCR0cqApE4XNvTdD9heJSFssRxRma5MIWbLp5q7 KuStqfVc5Mi7/uCEtKU/XidV25HekngkokdSavKrGmFA9IR6yxAQ/fT2R/UVEXUpOV JshYWFM1jRBiauogMI9LETcKUpSEg7rlt/XCrsDvHcIcKKrKf+Lfu9grpGXEUlOUBw il1cziT3er+LG8IbGUfsHyBhUl9fEmWujhzvys7fEbuJMHuqJFLv3DIRlBTxlslyyu 1lR419jEJXKMw== 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 v2 17/51] s390/dasd: don't look in front of the buffer on an empty write Date: Wed, 4 Nov 2026 18:47:03 +0100 Message-ID: <20261104-work-procfs-bugfixes-v2-17-bbf7d5546809@kernel.org> In-Reply-To: <20261104-work-procfs-bugfixes-v2-0-bbf7d5546809@kernel.org> References: <20261104-work-procfs-bugfixes-v2-0-bbf7d5546809@kernel.org> X-Mailing-List: linux-wireless@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=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9zrsssUymaabA31Var5avOM5bfCJp4gvZaynZy78sz mbbvsPjXUcpC4MYF4OsmCKLQ7tJuNxynorNRpkaMHNYmUCGMHBxCsBEJKczMuyYrr82Yt6rR8wV ngvXr6z7d1Hu7s13rzfk5t00zdb9H3OckeGStmp/GZ/E1KSXmfqdfP1HWkLun/hu9/dXSsq18Bl 8+mwA 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