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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=mYzQuqq1; 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 8BCAD6070B0B; Wed, 4 Nov 2026 17:52:29 +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=mYzQuqq1 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5214C1F00919; Wed, 4 Nov 2026 17:52:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793814749; bh=yb3WLcVokXU6BuV8DQIS3cnoxrtkXR+HXTNSt4lhnr4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mYzQuqq14/wTRRzzUwsG17Ab+8tgoUHpySPnl84Mr25NNzcLhEp7Tq87twOltFKtA dLD4dH0S9ylQ5twpfaifjPBB9F9nLw9N+znijKLYLcOnWkObGODYTAZeChhNq2O2Ca IQI8NCRh7J2BZ5sI7mVRJjsoRWd+WGQFkSSMno0hv8VCeplcjuV9ER78Y79IneS3ww A/5asZFiMwgLRWg3CnX7bPRgzhBlLJJ299YG81hHCGwYVIYI6Vtka99WENBzIlbtj9 RDwPxtwzVpVgN2qYy6WEMTlYIhf+ZUrM+RRJ4JaWwLGuxFHxYcI/kP7k045W27PJnL 9gvSnUTnaD3zQ== 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 27/51] um: NUL-terminate what is written to /proc/exitcode Date: Wed, 4 Nov 2026 18:47:13 +0100 Message-ID: <20261104-work-procfs-bugfixes-v2-27-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-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=1042; i=brauner@kernel.org; h=from:subject:message-id; bh=wRElBRQ5ywf1BhvCA77KtICLks8yyr6GFoKnZLCCyMo=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9znsQFfC+I/C0Ra1Qv94XtoNfmEzj9zwr/ak74frKN 6dmt7y52lHKwiDGxSArpsji0G4SLrecp2KzUaYGzBxWJpAhDFycAjCRvl6Gf8ru0zvmyVXlJJn5 RX64VRT8c5vVqQOhHe+XJk+QCA1678rI0PD9gNXt6xMOWujrbTe9wyTBv3D/B9HmPSse+sbVn4l X4wAA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: 8bit exitcode_proc_write() copies up to sizeof(buf) bytes of the write into buf and hands it to simple_strtol() without terminating it. So "echo -n 5" parses whatever the stack held after the '5', and a write of seven bytes or more reads past the end of buf. Terminate the copy. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner (Amutable) --- arch/um/kernel/exitcode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/um/kernel/exitcode.c b/arch/um/kernel/exitcode.c index 43edc2aa57e4..0230354f4812 100644 --- a/arch/um/kernel/exitcode.c +++ b/arch/um/kernel/exitcode.c @@ -43,9 +43,10 @@ static ssize_t exitcode_proc_write(struct file *file, size_t size; int tmp; - size = min(count, sizeof(buf)); + size = min(count, sizeof(buf) - 1); if (copy_from_user(buf, buffer, size)) return -EFAULT; + buf[size] = '\0'; tmp = simple_strtol(buf, &end, 0); if ((*end != '\0') && !isspace(*end)) -- 2.53.0