>From a483c5673cef7995e74dc3556196e25344b5e434 Mon Sep 17 00:00:00 2001 From: Gopi Krishna Menon Date: Tue, 28 Oct 2025 20:18:04 +0530 Subject: [PATCH] usb: raw-gadget: cap raw_io transfer length to KMALLOC_MAX_SIZE To: andreyknvl@gmail.com, gregkh@linuxfoundation.org Cc: snovitoll@gmail.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, david.hunter.linux@gmail.com, khalid@kernel.org, linux-kernel-mentees@lists.linux.dev, syzbot+d8fd35fa6177afa8c92b@syzkaller.appspotmail.com 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 --- drivers/usb/gadget/legacy/raw_gadget.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/usb/gadget/legacy/raw_gadget.c b/drivers/usb/gadget/legacy/raw_gadget.c index b71680c58de6..46f343ba48b3 100644 --- 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 { -- 2.43.0