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Mon, 2 Nov 2026 14:22:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793629391; bh=MVs7ALsfOLkn53l0kYUUme/SDUyhPHOVCY6QDFUmXzg=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=FLfR5DFeQsSly/cabaQC7e9iY2bQ9zaa9/+MREBD4BU88eN1Xx3KqTRtm3qYQYpfl kCDavrMTvPYKs/rYn9gptjjElebcf4yPuRmKH7HVcqjqazHfqUR/Htiq7M6QYbzt4U zWa4rzDSZK1q8pK7OQVMGrLrU+xIoyILoyQv+YpF94q5kGFQx5QO63A+aw0aYwigp7 8QwH/5quUO5K2fuIJpTTFlJf5GF8Ltsg0OQYaZW1HbdncmCkutEph8u81EsuVQiORQ PSv2MLOMncLKFj4vxCZCl4sIAOggQ39Y2OGr1AHxp6406Vqv9fSst95zy3PsIJt0ea Hqf1VPSexzNvw== From: Christian Brauner Date: Mon, 02 Nov 2026 15:21:21 +0100 Subject: [PATCH RFC 06/38] xtensa: simdisk: don't read the file name without the lock X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261102-work-procfs-bugfixes-v1-6-59422ed3e465@kernel.org> References: <20261102-work-procfs-bugfixes-v1-0-59422ed3e465@kernel.org> In-Reply-To: <20261102-work-procfs-bugfixes-v1-0-59422ed3e465@kernel.org> 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 X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=1811; i=brauner@kernel.org; h=from:subject:message-id; bh=VTDmn8Fj5UlymIH+0OFfDD9d3Id2xocQBgXcavnnib4=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9mJP1/VRcytoDLK0ufy3WLzr3+sXFE+dzGyTVYqofd O+7u3tWckcpC4MYF4OsmCKLQ7tJuNxynorNRpkaMHNYmUCGMHBxCsBEUkQZ/rs27hJY5+amu8Rq WoJCkbXlpumL4jqiOpe4HNF66TkndBkjwwvt4L3fvCaeXKnVx7hb7eIq/dqmQN78dydXJQe4lqT uZgEA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" X-Spam-Status: No, score=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 proc_read_simdisk() looks at dev->filename without holding dev->lock. A write to the same file detaches the disk and frees the name under the lock, so a concurrent reader can copy out freed memory. Copy the name with the lock held. Fixes: b6c7e873daf7 ("xtensa: ISS: add host file-based simulated disk") Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner (Amutable) --- arch/xtensa/platforms/iss/simdisk.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/arch/xtensa/platforms/iss/simdisk.c b/arch/xtensa/platforms/iss/simdisk.c index a2ddb49c269d..7b115e023de9 100644 --- a/arch/xtensa/platforms/iss/simdisk.c +++ b/arch/xtensa/platforms/iss/simdisk.c @@ -238,22 +238,21 @@ static ssize_t proc_read_simdisk(struct file *file, char __user *buf, size_t size, loff_t *ppos) { struct simdisk *dev = pde_data(file_inode(file)); - const char *s = dev->filename; - if (s) { - ssize_t len = strlen(s); - char *temp = kmalloc(len + 2, GFP_KERNEL); + ssize_t len; + char *temp; - if (!temp) - return -ENOMEM; + /* a write sets at most a page, see proc_write_simdisk() */ + temp = kmalloc(PAGE_SIZE + 2, GFP_KERNEL); + if (!temp) + return -ENOMEM; - len = scnprintf(temp, len + 2, "%s\n", s); - len = simple_read_from_buffer(buf, size, ppos, - temp, len); + spin_lock(&dev->lock); + len = scnprintf(temp, PAGE_SIZE + 2, "%s\n", dev->filename ?: ""); + spin_unlock(&dev->lock); - kfree(temp); - return len; - } - return simple_read_from_buffer(buf, size, ppos, "\n", 1); + len = simple_read_from_buffer(buf, size, ppos, temp, len); + kfree(temp); + return len; } static ssize_t proc_write_simdisk(struct file *file, const char __user *buf, -- 2.53.0