In the Linux kernel, the following vulnerability has been resolved:
media: rtl2832_sdr: release URBs and stream buffers on start_streaming() failure
rtl2832_sdr_start_streaming() calls rtl2832_sdr_alloc_stream_bufs(),
rtl2832_sdr_alloc_urbs() and rtl2832_sdr_submit_urbs() in sequence and
shares a single err: label that only unlocks the mutex and returns.
When alloc_urbs() succeeds but submit_urbs() fails, or when alloc_urbs()
itself returns -ENOMEM after alloc_stream_bufs() has already succeeded,
the URBs and/or the coherent DMA stream buffers stay allocated while
streaming reports failure to vb2. Two latent defects follow on the next
VIDIOC_STREAMON:
1) rtl2832_sdr_alloc_stream_bufs() unconditionally resets dev->buf_num
to 0 and overwrites dev->buf_list[]/dev->dma_addr[], permanently
leaking the coherent DMA memory allocated by the previous attempt.
2) rtl2832_sdr_alloc_urbs() never resets dev->urbs_initialized and only
increments it. After a second successful pass urbs_initialized can
exceed MAX_BULK_BUFS, so the subsequent rtl2832_sdr_free_urbs() walks
from urbs_initialized - 1 down to 0 and reads past the end of
dev->urb_list[], passing garbage pointers to usb_free_urb().
Mirror the teardown that stop_streaming() already performs: on the error
path call rtl2832_sdr_free_urbs() and rtl2832_sdr_free_stream_bufs()
before unlocking. Both helpers are idempotent (free_urbs kills and zeros
urbs_initialized; free_stream_bufs is gated on URB_BUF and clears the
buf_num counter), so partial-failure paths and the no-allocation paths
remain safe.
Issue identified by automated review of the INV-003 series at
https://sashiko.dev/
CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 7.8
AV:L - The flaw is reached only through local V4L2 ioctls (VIDIOC_REQBUFS, VIDIOC_QBUF, VIDIOC_STREAMON) on the rtl2832_sdr /dev/swradioN node; USB bulk packets from the dongle never enter this start_streaming() error path.
AC:L - The attacker drives both STREAMON attempts and can force the first submit_urbs() failure via USBDEVFS_RESET/DISCONNECT on the matching usbfs node or GFP_KERNEL memory pressure, then retry STREAMON; no race or layout outside their control is required.
PR:L - v4l2_fh_open() and vb2_ioctl_streamon() perform no capability checks; only the SDR device node is needed, and udev uaccess/video-group rules grant it to unprivileged seat users on desktops, Android, and embedded RTL-SDR systems.
UI:N - The attacking process issues REQBUFS/QBUF/STREAMON (and any usbfs reset) on its own file descriptors against an already-attached RTL2832; no separate victim action such as plugging in the dongle or opening a file is required.
S:U - The urb_list[] overrun, leaked coherent DMA buffers, and resulting usb_submit_urb()/usb_free_urb() misuse stay in host kernel memory in the same OS security authority; no VM, IOMMU, or sandbox boundary is crossed.
C:H - After a failed STREAMON, a second alloc_urbs() leaves urbs_initialized above MAX_BULK_BUFS, so submit_urbs()/free_urbs() read past urb_list[] and treat adjacent kernel fields (including live buf_list[] DMA pointers) as struct urb objects, an out-of-bounds/type-confused kernel read.
I:H - usb_submit_urb() writes urb->ep/status/transfer_flags through those OOB-derived pointers, and the subsequent free_urbs() walk passes the same garbage to usb_free_urb()/kref_put, a type-confusion/slab-corruption write primitive suitable for control-flow hijack.
A:H - usb_submit_urb() of the first out-of-bounds slot oopses the kernel (near-NULL from buf_num), and the attacker can repeat STREAMON after a forced submit failure to panic or hang the host at will.
| Attack Vector |
Local |
Scope |
Unchanged |
| Attack Complexity |
Low |
Confidentiality Impact |
High |
| Privileges Required |
Low |
Integrity Impact |
High |
| User Interaction |
None |
Availability Impact |
High |
AV:L - The flaw is reached only through local V4L2 ioctls (VIDIOC_REQBUFS, VIDIOC_QBUF, VIDIOC_STREAMON) on the rtl2832_sdr /dev/swradioN node; USB bulk packets from the dongle never enter this start_streaming() error path.
AC:L - The attacker drives both STREAMON attempts and can force the first submit_urbs() failure via USBDEVFS_RESET/DISCONNECT on the matching usbfs node or GFP_KERNEL memory pressure, then retry STREAMON; no race or layout outside their control is required.
PR:L - v4l2_fh_open() and vb2_ioctl_streamon() perform no capability checks; only the SDR device node is needed, and udev uaccess/video-group rules grant it to unprivileged seat users on desktops, Android, and embedded RTL-SDR systems.
UI:N - The attacking process issues REQBUFS/QBUF/STREAMON (and any usbfs reset) on its own file descriptors against an already-attached RTL2832; no separate victim action such as plugging in the dongle or opening a file is required.
S:U - The urb_list[] overrun, leaked coherent DMA buffers, and resulting usb_submit_urb()/usb_free_urb() misuse stay in host kernel memory in the same OS security authority; no VM, IOMMU, or sandbox boundary is crossed.
C:H - After a failed STREAMON, a second alloc_urbs() leaves urbs_initialized above MAX_BULK_BUFS, so submit_urbs()/free_urbs() read past urb_list[] and treat adjacent kernel fields (including live buf_list[] DMA pointers) as struct urb objects, an out-of-bounds/type-confused kernel read.
I:H - usb_submit_urb() writes urb->ep/status/transfer_flags through those OOB-derived pointers, and the subsequent free_urbs() walk passes the same garbage to usb_free_urb()/kref_put, a type-confusion/slab-corruption write primitive suitable for control-flow hijack.
A:H - usb_submit_urb() of the first out-of-bounds slot oopses the kernel (near-NULL from buf_num), and the attacker can repeat STREAMON after a forced submit failure to panic or hang the host at will.
CVSS 3.1