CVE-2025-21976

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> fbdev: hyperv_fb: Allow graceful removal of framebuffer<br /> <br /> When a Hyper-V framebuffer device is unbind, hyperv_fb driver tries to<br /> release the framebuffer forcefully. If this framebuffer is in use it<br /> produce the following WARN and hence this framebuffer is never released.<br /> <br /> [ 44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40<br /> <br /> [ 44.111289] Call Trace:<br /> [ 44.111290] <br /> [ 44.111291] ? show_regs+0x6c/0x80<br /> [ 44.111295] ? __warn+0x8d/0x150<br /> [ 44.111298] ? framebuffer_release+0x2c/0x40<br /> [ 44.111300] ? report_bug+0x182/0x1b0<br /> [ 44.111303] ? handle_bug+0x6e/0xb0<br /> [ 44.111306] ? exc_invalid_op+0x18/0x80<br /> [ 44.111308] ? asm_exc_invalid_op+0x1b/0x20<br /> [ 44.111311] ? framebuffer_release+0x2c/0x40<br /> [ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb]<br /> [ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus]<br /> [ 44.111323] device_remove+0x40/0x80<br /> [ 44.111325] device_release_driver_internal+0x20b/0x270<br /> [ 44.111327] ? bus_find_device+0xb3/0xf0<br /> <br /> Fix this by moving the release of framebuffer and assosiated memory<br /> to fb_ops.fb_destroy function, so that framebuffer framework handles<br /> it gracefully.<br /> <br /> While we fix this, also replace manual registrations/unregistration of<br /> framebuffer with devm_register_framebuffer.