CVE-2024-35932: drm/vc4: don't check if plane->state->fb == state->fb

Description

In the Linux kernel, the following vulnerability has been resolved:

drm/vc4: don't check if plane->state->fb == state->fb

Currently, when using non-blocking commits, we can see the following
kernel warning:

[ 110.908514] ------------[ cut here ]------------
[ 110.908529] refcount_t: underflow; use-after-free.
[ 110.908620] WARNING: CPU: 0 PID: 1866 at lib/refcount.c:87 refcount_dec_not_one+0xb8/0xc0
[ 110.908664] Modules linked in: rfcomm snd_seq_dummy snd_hrtimer snd_seq snd_seq_device cmac algif_hash aes_arm64 aes_generic algif_skcipher af_alg bnep hid_logitech_hidpp vc4 brcmfmac hci_uart btbcm brcmutil bluetooth snd_soc_hdmi_codec cfg80211 cec drm_display_helper drm_dma_helper drm_kms_helper snd_soc_core snd_compress snd_pcm_dmaengine fb_sys_fops sysimgblt syscopyarea sysfillrect raspberrypi_hwmon ecdh_generic ecc rfkill libaes i2c_bcm2835 binfmt_misc joydev snd_bcm2835(C) bcm2835_codec(C) bcm2835_isp(C) v4l2_mem2mem videobuf2_dma_contig snd_pcm bcm2835_v4l2(C) raspberrypi_gpiomem bcm2835_mmal_vchiq(C) videobuf2_v4l2 snd_timer videobuf2_vmalloc videobuf2_memops videobuf2_common snd videodev vc_sm_cma(C) mc hid_logitech_dj uio_pdrv_genirq uio i2c_dev drm fuse dm_mod drm_panel_orientation_quirks backlight ip_tables x_tables ipv6
[ 110.909086] CPU: 0 PID: 1866 Comm: kodi.bin Tainted: G C 6.1.66-v8+ #32
[ 110.909104] Hardware name: Raspberry Pi 3 Model B Rev 1.2 (DT)
[ 110.909114] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 1...

Classification

CVE ID: CVE-2024-35932

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.05% (probability of being exploited)

EPSS Percentile: 17.83% (scored less or equal to compared to others)

EPSS Date: 2025-02-04 (when was this score calculated)

References

https://git.kernel.org/stable/c/48bfb4b03c5ff6e1fa1dc73fb915e150b0968c40
https://git.kernel.org/stable/c/d6b2fe2db1d0927b2d7df5c763eba55d0e1def3c
https://git.kernel.org/stable/c/5343f724c912c77541029123f47ecd3d2ea63bdd
https://git.kernel.org/stable/c/5ee0d47dcf33efd8950b347dcf4d20bab12a3fa9

Timeline