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Mon, 2 Nov 2026 14:21:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793629323; bh=0oFqdYtQQ93hmf66Xu9P3kJmoMCkLJeiEqd5UgVqoAA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=ax8dWQyerzpr/lWF0zvdG4jamemgWlVZd/h7GMRXnqhpTBDJEl7ev50HTLs6gH7J/ 0p7NNLryksO6UgSelTjy18+WNSqy3gYWlFUSSyR19sqLhSv0hd9SLP5IvSKwiIx0nB EmF9BtAu7NyghltI+OycSZEJ26mnAtmx7MkuIud4BVq2NcIGDOUtdlbiumRpD8YiX6 cay+Ggorj7ZVDVBu7GBPEK5Aw51B56VDfiDPqSmzWSFRn7vWnbSOjeXUnaCNUmE3rR czSLGyB9rAbV56X/5L4Tebo1G1sdy4cG9DZlv5tDH9WHwzjWU8tayWaP5twT6EmNQp RARmDivxEu4rw== From: Christian Brauner Date: Mon, 02 Nov 2026 15:21:16 +0100 Subject: [PATCH RFC 01/38] PCI/proc: don't truncate the position of config space accesses X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , Precedence: list X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261102-work-procfs-bugfixes-v1-1-59422ed3e465@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=2714; i=brauner@kernel.org; h=from:subject:message-id; bh=57Zv3BgjxHPYJgAYtfWWUhWCD6jzurA4v7Zp2iJg+04=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9mJN11v/UUrXtFcJuaV4rJB5G2Ou5n+Tu6Z/jVp+uW MTK/0yqo5SFQYyLQVZMkcWh3SRcbjlPxWajTA2YOaxMIEMYuDgFYCK7NzH8M2yqMdxuWRuoE37x QsuKJx8C/3tt2Xjyxk6p05Y/GGTn7WJkeKXl8emh1r1VXHuO8HVGP7z6emFsq1zH7SfFda/fuJx cwwoA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 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-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 proc_bus_pci_write() truncates the file position to an int. A pwrite() at an offset like 0xfffff000 turns it negative, the check against the size of the config space passes and the count it clamps to ends up larger than what was written. The loop then reads past the end of the caller's buffer and writes all of it into config space at negative offsets, which pci_user_write_config_*() pass on to the config accessors unchecked. The write also returns more than it was asked to write. An offset above 4G that truncates to a small positive value writes to the start of config space instead. proc_bus_pci_read() keeps the position in an unsigned int, so a read at such an offset returns the start of config space instead of hitting EOF. Check the position against the size of the config space before narrowing it. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner (Amutable) --- drivers/pci/proc.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index 3d7a9ed5fc22..e0dc70123f82 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -32,8 +32,7 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) { struct pci_dev *dev = pde_data(file_inode(file)); - unsigned int pos = *ppos; - unsigned int cnt, size; + unsigned int pos, cnt, size; /* * Normal users can read only the standardized portion of the @@ -51,8 +50,9 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf, if (!nbytes) return 0; - if (pos >= size) + if (*ppos >= size) return 0; + pos = *ppos; if (nbytes >= size) nbytes = size; if (pos + nbytes > size) @@ -119,9 +119,8 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf, { struct inode *ino = file_inode(file); struct pci_dev *dev = pde_data(ino); - int pos = *ppos; int size = dev->cfg_size; - int cnt, ret; + int pos, cnt, ret; ret = security_locked_down(LOCKDOWN_PCI_ACCESS); if (ret) @@ -130,14 +129,16 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf, if (!nbytes) return 0; + if (*ppos >= size) + return 0; + pos = *ppos; + if (resource_is_exclusive(&dev->driver_exclusive_resource, pos, nbytes)) { pci_warn_once(dev, "%s: Unexpected write to kernel-exclusive config offset %x", current->comm, pos); add_taint(TAINT_USER, LOCKDEP_STILL_OK); } - if (pos >= size) - return 0; if (nbytes >= size) nbytes = size; if (pos + nbytes > size) -- 2.53.0