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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-Archived-By: 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 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam09 X-Stat-Signature: h9u3pgtohn63zaaxopznk96gtrzd394m X-Rspamd-Queue-Id: 71D8710000C X-Rspam-User: X-HE-Tag: 1793820022-189097 X-HE-Meta: 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 wifSnsnh d0e26H23/NrWo16OsAqzIyMDWf087sJSQLRo7TCsE2ttSZOa/ezsxCgaQwF/TVC5UogBz4TMKCzR3/nQvA32QLNohFXIZRpuLm7BQCzqBXkODxie8ee3gWSpJFuDBu3TPFjsHEJvRf3rN6Y7pKpPGRx6K8a3pmZRiOyW4f/j7VTiJX7Bb0asV0/S0MTFGHgsbCNLAnrIrItDGAJ5vRnRVer5CWvTcpSmHaBcxLQRyMo8kEqrxR6o5w9Y7kPURfOFIaMm48XcoxX10/RHZE+8fqN83WbOgKQCXQN3BFJRHFniLugyOtHC8PBOTCA13s6hNedaY2wbujvxa/gkdYuMk6iqeA5gmqmr8TNMPn8FESA5zejrYxaKZOXbHrZV24TA6g0tx9GQaS2UVDR73nMBOnhuIkTrWIOHI58OLl2Mgn1z0Z8hmk8f5Ehcixg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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