In the Linux kernel, the following vulnerability has been resolved:drm/fbdev-dma: Only set smem_start is enable per module optionOnly export struct fb_info.fix.smem_start if that is required by theuser and the memory does not come from vmalloc().Setting struct fb_info.fix.smem_start breaks systems where DMAmemory is backed by vmalloc address space. An example error isshown below. 3.536043] ------------[ cut here ]------------[ 3.540716] virt_to_phys used for non-linear address: 000000007fc4f540 (0xffff800086001000)[ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 __virt_to_phys+0x68/0x98[ 3.565455] Modules linked in:[ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted 6.6.23-06226-g4986cc3e1b75-dirty #250[ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)[ 3.582452] Workqueue: events_unbound deferred_probe_work_func[ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)[ 3.595233] pc : __virt_to_phys+0x68/0x98[ 3.599246] lr : __virt_to_phys+0x68/0x98[ 3.603276] sp : ffff800083603990[ 3.677939] Call trace:[ 3.680393] __virt_to_phys+0x68/0x98[ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238[ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0[ 3.695385] drm_fb_helper_initial_config+0x4c/0x68[ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0[ 3.705161] drm_client_register+0x60/0xb0[ 3.709269] drm_fbdev_dma_setup+0x94/0x148Additionally, DMA memory is assumed to by contiguous in physicaladdress space, which is not guaranteed by vmalloc().Resolve this by checking the module flag drm_leak_fbdev_smem whenDRM allocated the instance of struct fb_info. Fbdev-dma then onlysets smem_start only if required (via FBINFO_HIDE_SMEM_START). Alsoguarantee that the framebuffer is not located in vmalloc addressspace. CREATE(Triage):(User=admin) [CVE-2024-41094 (https://nvd.nist.gov/vuln/detail/CVE-2024-41094)
