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([2405:201:682f:383f:746c:8928:e990:23a8]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-315bec128a0sm30150480eec.25.2026.08.08.21.59.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Aug 2026 21:59:53 -0700 (PDT) From: Deepanshu Kartikey To: bhelgaas@google.com Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+7134530b25073b4ef373@syzkaller.appspotmail.com Subject: [PATCH] PCI: sysfs: Reject unaligned resource I/O port accesses Date: Sun, 9 Aug 2026 10:29:46 +0530 Message-ID: <20260809045946.15638-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit pci_resource_io() validates that off+count stays within the BAR's range but never checks that the resulting port is aligned to the access size. A pwrite64()/pread64() on a resourceN file with an odd offset and count=2 or count=4 reaches outw()/outl() with a misaligned address. On arm64 this becomes a store/load to a Device-memory mapping (PCI_IOBASE + port), which architecturally requires natural alignment, causing an alignment fault and kernel oops. Reject misaligned accesses before they reach the low-level accessor. Reported-by: syzbot+7134530b25073b4ef373@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7134530b25073b4ef373 Signed-off-by: Deepanshu Kartikey --- drivers/pci/pci-sysfs.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 5ec0b245a69b..72f0404a34e9 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1175,6 +1175,9 @@ static ssize_t pci_resource_io(struct file *filp, struct kobject *kobj, if (port + count - 1 > pci_resource_end(pdev, bar)) return -EINVAL; + if (!IS_ALIGNED(port, count)) + return -EINVAL; + switch (count) { case 1: if (write) -- 2.43.0