From: Lee Jones <lee@xxxxxxxxxx> commit 6d3c721e686ea6c59e18289b400cc95c76e927e0 upstream. Userspace provided string 's' could trivially have the length zero. Left unchecked this will firstly result in an OOB read in the form `if (str[0 - 1] == '\n') followed closely by an OOB write in the form `str[0 - 1] = '\0'`. There is already a validating check to catch strings that are too long. Let's supply an additional check for invalid strings that are too short. Signed-off-by: Lee Jones <lee@xxxxxxxxxx> Cc: stable <stable@xxxxxxxxxx> Link: https://lore.kernel.org/r/20240705074339.633717-1-lee@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/gadget/configfs.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/usb/gadget/configfs.c +++ b/drivers/usb/gadget/configfs.c @@ -116,9 +116,12 @@ static int usb_string_copy(const char *s int ret; char *str; char *copy = *s_copy; + ret = strlen(s); if (ret > USB_MAX_STRING_LEN) return -EOVERFLOW; + if (ret < 1) + return -EINVAL; if (copy) { str = copy; Patches currently in stable-queue which might be from lee@xxxxxxxxxx are queue-4.19/usb-gadget-configfs-prevent-oob-read-write-in-usb_string_copy.patch
