diff options
| author | Jann Horn <jannh@google.com> | 2024-10-16 17:24:06 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-10-17 08:36:52 +0200 |
| commit | 3ea36dc8ddd72d92d737612507f98dfaf3b77c3f (patch) | |
| tree | 71dc9a3f7b55b84b211e0259aa9870aa9cdf5c9d /drivers/usb/core | |
| parent | 7b5a58952fc3b51905c2963647485565df1e5e26 (diff) | |
usb: require FMODE_WRITE for usbdev_mmap()
usbdev_mmap() creates VMAs which can only be used through
usbdev_do_ioctl(), which requires FMODE_WRITE; so usbdev_mmap() is only
useful with FMODE_WRITE.
On typical Linux systems, files at /dev/bus/usb/*/* are mode 0664, so
UIDs without any special privileges can't use usbdev_do_ioctl(), but
they can still execute the usbdev_mmap() codepath.
Check for FMODE_WRITE in usbdev_mmap() to reduce attack surface a little
bit.
Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20241016-usbdev-mmap-require-write-v1-1-6f8256414d5c@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core')
| -rw-r--r-- | drivers/usb/core/devio.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 3beb6a862e80..5363468a282f 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -238,6 +238,9 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) dma_addr_t dma_handle = DMA_MAPPING_ERROR; int ret; + if (!(file->f_mode & FMODE_WRITE)) + return -EPERM; + ret = usbfs_increase_memory_usage(size + sizeof(struct usb_memory)); if (ret) goto error; |