5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Krzysztof Wilczyński [ Upstream commit 92742802ecbf215a2b60dcfd326d2213595010f1 ] pci_write_rom() controls access to the ROM content through the corresponding sysfs attribute, and treats the input as a request to disable only when it matches the string "0\n" exactly: if ((off == 0) && (*buf == '0') && (count == 2)) The count == 2 condition encodes the trailing newline that echo(1) appends. This was found when userspace wrote "0" without a trailing newline aiming to disable access, which failed to match the condition above and enabled access instead. For example: $ echo 0 > rom # "0\n", count 2, access disabled $ echo -n 0 > rom # "0", count 1, access enabled $ echo > rom # "", count 1, access enabled (likely not desirable) Parse the input with kstrtobool(), which handles common boolean inputs such as "0", "1", "n", "y" or "off", "on", with or without a trailing newline, so both of the above disable access, and update the now stale comment. As a side effect, input that does not parse as a boolean is rejected with -EINVAL rather than enabling access. The documented "0" and "1" continue to work as before, and rejecting malformed input brings the attribute in line with how sysfs attributes typically handle it. Signed-off-by: Krzysztof Wilczyński Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20260612182448.552406-1-kwilczynski@kernel.org Signed-off-by: Sasha Levin --- drivers/pci/pci-sysfs.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 33847e32fb429..69f44a4e14064 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1343,18 +1343,19 @@ void __weak pci_remove_resource_files(struct pci_dev *dev) { return; } * @off: file offset * @count: number of byte in input * - * writing anything except 0 enables it + * Writing a boolean value enables or disables the ROM display. */ static ssize_t pci_write_rom(struct file *filp, struct kobject *kobj, struct bin_attribute *bin_attr, char *buf, loff_t off, size_t count) { struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj)); + bool enable; - if ((off == 0) && (*buf == '0') && (count == 2)) - pdev->rom_attr_enabled = 0; - else - pdev->rom_attr_enabled = 1; + if (kstrtobool(buf, &enable)) + return -EINVAL; + + pdev->rom_attr_enabled = enable; return count; } -- 2.53.0