usb: raw-gadget: cap raw_io transfer length to KMALLOC_MAX_SIZE

The previous commit removed the PAGE_SIZE limit on transfer length of
raw_io buffer in order to avoid any problems with emulating USB devices
whose full configuration descriptor exceeds PAGE_SIZE in length. However
this also removes the upperbound on user supplied length, allowing very
large values to be passed to the allocator.

syzbot on fuzzing the transfer length with very large value (1.81GB)
results in kmalloc() to fall back to the page allocator, which triggers
a kernel warning as the page allocator cannot handle allocations more
than MAX_PAGE_ORDER/KMALLOC_MAX_SIZE.

Since there is no limit imposed on the size of buffer for both control
and non control transfers, cap the raw_io transfer length to
KMALLOC_MAX_SIZE and return -EINVAL for larger transfer length to
prevent any warnings from the page allocator.

Fixes: 37b9dd0d114a ("usb: raw-gadget: do not limit transfer length")
Tested-by: syzbot+d8fd35fa6177afa8c92b@syzkaller.appspotmail.com
Reported-by: syzbot+d8fd35fa6177afa8c92b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68fc07a0.a70a0220.3bf6c6.01ab.GAE@google.com/
Signed-off-by: Gopi Krishna Menon <krishnagopi487@gmail.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://patch.msgid.link/20251028165659.50962-1-krishnagopi487@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/legacy/raw_gadget.c b/drivers/usb/gadget/legacy/raw_gadget.c
index b71680c58de6c73e42d1df49ddd399915ab001f2..46f343ba48b3da0793786600a904b912a0ab437c 100644 (file)
--- a/drivers/usb/gadget/legacy/raw_gadget.c
+++ b/drivers/usb/gadget/legacy/raw_gadget.c
@@ -40,6 +40,7 @@ MODULE_LICENSE("GPL");
 
 static DEFINE_IDA(driver_id_numbers);
 #define DRIVER_DRIVER_NAME_LENGTH_MAX  32
+#define USB_RAW_IO_LENGTH_MAX KMALLOC_MAX_SIZE
 
 #define RAW_EVENT_QUEUE_SIZE   16
 
@@ -667,6 +668,8 @@ static void *raw_alloc_io_data(struct usb_raw_ep_io *io, void __user *ptr,
                return ERR_PTR(-EINVAL);
        if (!usb_raw_io_flags_valid(io->flags))
                return ERR_PTR(-EINVAL);
+       if (io->length > USB_RAW_IO_LENGTH_MAX)
+               return ERR_PTR(-EINVAL);
        if (get_from_user)
                data = memdup_user(ptr + sizeof(*io), io->length);
        else {