From: Saurabh Sengar <ssengar@linux.microsoft.com> mainline inclusion from mainline-v6.14-rc7 commit ea2f45ab0e53b255f72c85ccd99e2b394fc5fceb category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBY436 CVE: CVE-2025-21976 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- When a Hyper-V framebuffer device is unbind, hyperv_fb driver tries to release the framebuffer forcefully. If this framebuffer is in use it produce the following WARN and hence this framebuffer is never released. [ 44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40 < snip > [ 44.111289] Call Trace: [ 44.111290] <TASK> [ 44.111291] ? show_regs+0x6c/0x80 [ 44.111295] ? __warn+0x8d/0x150 [ 44.111298] ? framebuffer_release+0x2c/0x40 [ 44.111300] ? report_bug+0x182/0x1b0 [ 44.111303] ? handle_bug+0x6e/0xb0 [ 44.111306] ? exc_invalid_op+0x18/0x80 [ 44.111308] ? asm_exc_invalid_op+0x1b/0x20 [ 44.111311] ? framebuffer_release+0x2c/0x40 [ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb] [ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus] [ 44.111323] device_remove+0x40/0x80 [ 44.111325] device_release_driver_internal+0x20b/0x270 [ 44.111327] ? bus_find_device+0xb3/0xf0 Fix this by moving the release of framebuffer and assosiated memory to fb_ops.fb_destroy function, so that framebuffer framework handles it gracefully. While we fix this, also replace manual registrations/unregistration of framebuffer with devm_register_framebuffer. Fixes: 68a2d20b79b1 ("drivers/video: add Hyper-V Synthetic Video Frame Buffer Driver") Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Michael Kelley <mhklinux@outlook.com> Link: https://lore.kernel.org/r/1740845791-19977-3-git-send-email-ssengar@linux.mi... Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1740845791-19977-3-git-send-email-ssengar@linux.microsoft.com> Conflicts: drivers/video/fbdev/hyperv_fb.c [context conflicts] Signed-off-by: Xiangwei Li <liwei728@huawei.com> --- drivers/video/fbdev/hyperv_fb.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c index 44cd0607d66b..a33b872cfc9b 100644 --- a/drivers/video/fbdev/hyperv_fb.c +++ b/drivers/video/fbdev/hyperv_fb.c @@ -283,6 +283,8 @@ static uint screen_depth; static uint screen_fb_size; static uint dio_fb_size; /* FB size for deferred IO */ +static void hvfb_putmem(struct fb_info *info); + /* Send message to Hyper-V host */ static inline int synthvid_send(struct hv_device *hdev, struct synthvid_msg *msg) @@ -887,6 +889,17 @@ static void hvfb_cfb_imageblit(struct fb_info *p, image->width, image->height); } +/* + * fb_ops.fb_destroy is called by the last put_fb_info() call at the end + * of unregister_framebuffer() or fb_release(). Do any cleanup related to + * framebuffer here. + */ +static void hvfb_destroy(struct fb_info *info) +{ + hvfb_putmem(info); + framebuffer_release(info); +} + static const struct fb_ops hvfb_ops = { .owner = THIS_MODULE, .fb_check_var = hvfb_check_var, @@ -897,6 +910,7 @@ static const struct fb_ops hvfb_ops = { .fb_imageblit = hvfb_cfb_imageblit, .fb_blank = hvfb_blank, .fb_mmap = fb_deferred_io_mmap, + .fb_destroy = hvfb_destroy, }; @@ -1198,7 +1212,7 @@ static int hvfb_probe(struct hv_device *hdev, if (ret) goto error; - ret = register_framebuffer(info); + ret = devm_register_framebuffer(&hdev->device, info); if (ret) { pr_err("Unable to register framebuffer\n"); goto error; @@ -1246,14 +1260,10 @@ static void hvfb_remove(struct hv_device *hdev) fb_deferred_io_cleanup(info); - unregister_framebuffer(info); cancel_delayed_work_sync(&par->dwork); vmbus_close(hdev->channel); hv_set_drvdata(hdev, NULL); - - hvfb_putmem(info); - framebuffer_release(info); } static int hvfb_suspend(struct hv_device *hdev) -- 2.25.1