kernel.git/drivers/video/fbdev/core/fbmem.c, branch linux-5.17.y

Revert "fbdev: Make fb_release() return -ENODEV if fbdev was unregistered"

2022-05-25T07:59:13Z

[ Upstream commit 135332f34ba2662bc1e32b5c612e06a8cc41a053 ] This reverts commit aafa025c76dcc7d1a8c8f0bdefcbe4eb480b2f6a. That commit attempted to fix a NULL pointer dereference, caused by the struct fb_info associated with a framebuffer device to not longer be valid when the file descriptor was closed. The issue was exposed by commit 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal"), which added a new path that goes through the struct device removal instead of directly unregistering the fb. Most fbdev drivers have issues with the fb_info lifetime, because call to framebuffer_release() from their driver's .remove callback, rather than doing from fbops.fb_destroy callback. This meant that due to this switch, the fb_info was now destroyed too early, while references still existed, while before it was simply leaked. The patch we're reverting here reinstated that leak, hence "fixed" the regression. But the proper solution is to fix the drivers to not release the fb_info too soon. Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220504115917.758787-1-javierm@redhat.com Signed-off-by: Sasha Levin

fbdev: Make fb_release() return -ENODEV if fbdev was unregistered

2022-05-12T10:32:40Z

[ Upstream commit aafa025c76dcc7d1a8c8f0bdefcbe4eb480b2f6a ] A reference to the framebuffer device struct fb_info is stored in the file private data, but this reference could no longer be valid and must not be accessed directly. Instead, the file_fb_info() accessor function must be used since it does sanity checking to make sure that the fb_info is valid. This can happen for example if the registered framebuffer device is for a driver that just uses a framebuffer provided by the system firmware. In that case, the fbdev core would unregister the framebuffer device when a real video driver is probed and ask to remove conflicting framebuffers. The bug has been present for a long time but commit 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal") unmasked it since the fbdev core started unregistering the framebuffers' devices associated. Fixes: 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal") Reported-by: Maxime Ripard Reported-by: Junxiao Chang Signed-off-by: Javier Martinez Canillas Reviewed-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220502135014.377945-1-javierm@redhat.com Signed-off-by: Sasha Levin

fbdev: Fix unregistering of framebuffers without device

2022-04-13T17:27:38Z

commit 0f525289ff0ddeb380813bd81e0f9bdaaa1c9078 upstream. OF framebuffers do not have an underlying device in the Linux device hierarchy. Do a regular unregister call instead of hot unplugging such a non-existing device. Fixes a NULL dereference. An example error message on ppc64le is shown below. BUG: Kernel NULL pointer dereference on read at 0x00000060 Faulting instruction address: 0xc00000000080dfa4 Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries [...] CPU: 2 PID: 139 Comm: systemd-udevd Not tainted 5.17.0-ae085d7f9365 #1 NIP: c00000000080dfa4 LR: c00000000080df9c CTR: c000000000797430 REGS: c000000004132fe0 TRAP: 0300 Not tainted (5.17.0-ae085d7f9365) MSR: 8000000002009033 CR: 28228282 XER: 20000000 CFAR: c00000000000c80c DAR: 0000000000000060 DSISR: 40000000 IRQMASK: 0 GPR00: c00000000080df9c c000000004133280 c00000000169d200 0000000000000029 GPR04: 00000000ffffefff c000000004132f90 c000000004132f88 0000000000000000 GPR08: c0000000015658f8 c0000000015cd200 c0000000014f57d0 0000000048228283 GPR12: 0000000000000000 c00000003fffe300 0000000020000000 0000000000000000 GPR16: 0000000000000000 0000000113fc4a40 0000000000000005 0000000113fcfb80 GPR20: 000001000f7283b0 0000000000000000 c000000000e4a588 c000000000e4a5b0 GPR24: 0000000000000001 00000000000a0000 c008000000db0168 c0000000021f6ec0 GPR28: c0000000016d65a8 c000000004b36460 0000000000000000 c0000000016d64b0 NIP [c00000000080dfa4] do_remove_conflicting_framebuffers+0x184/0x1d0 [c000000004133280] [c00000000080df9c] do_remove_conflicting_framebuffers+0x17c/0x1d0 (unreliable) [c000000004133350] [c00000000080e4d0] remove_conflicting_framebuffers+0x60/0x150 [c0000000041333a0] [c00000000080e6f4] remove_conflicting_pci_framebuffers+0x134/0x1b0 [c000000004133450] [c008000000e70438] drm_aperture_remove_conflicting_pci_framebuffers+0x90/0x100 [drm] [c000000004133490] [c008000000da0ce4] bochs_pci_probe+0x6c/0xa64 [bochs] [...] [c000000004133db0] [c00000000002aaa0] system_call_exception+0x170/0x2d0 [c000000004133e10] [c00000000000c3cc] system_call_common+0xec/0x250 The bug [1] was introduced by commit 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal"). Most firmware framebuffers have an underlying platform device, which can be hot-unplugged before loading the native graphics driver. OF framebuffers do not (yet) have that device. Fix the code by unregistering the framebuffer as before without a hot unplug. Tested with 5.17 on qemu ppc64le emulation. Signed-off-by: Thomas Zimmermann Fixes: 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal") Reported-by: Sudip Mukherjee Reviewed-by: Daniel Vetter Reviewed-by: Javier Martinez Canillas Tested-by: Sudip Mukherjee Cc: Zack Rusin Cc: Javier Martinez Canillas Cc: Hans de Goede Cc: stable@vger.kernel.org # v5.11+ Cc: Helge Deller Cc: Daniel Vetter Cc: Sam Ravnborg Cc: Zheyu Ma Cc: Xiyu Yang Cc: Zhen Lei Cc: Matthew Wilcox Cc: Alex Deucher Cc: Tetsuo Handa Cc: Guenter Roeck Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Link: https://lore.kernel.org/all/YkHXO6LGHAN0p1pq@debian/ # [1] Link: https://patchwork.freedesktop.org/patch/msgid/20220404194402.29974-1-tzimmermann@suse.de Signed-off-by: Greg Kroah-Hartman

fbdev: Hot-unplug firmware fb devices on forced removal

2022-04-08T11:57:26Z

commit 27599aacbaefcbf2af7b06b0029459bbf682000d upstream. Hot-unplug all firmware-framebuffer devices as part of removing them via remove_conflicting_framebuffers() et al. Releases all memory regions to be acquired by native drivers. Firmware, such as EFI, install a framebuffer while posting the computer. After removing the firmware-framebuffer device from fbdev, a native driver takes over the hardware and the firmware framebuffer becomes invalid. Firmware-framebuffer drivers, specifically simplefb, don't release their device from Linux' device hierarchy. It still owns the firmware framebuffer and blocks the native drivers from loading. This has been observed in the vmwgfx driver. [1] Initiating a device removal (i.e., hot unplug) as part of remove_conflicting_framebuffers() removes the underlying device and returns the memory range to the system. [1] https://lore.kernel.org/dri-devel/20220117180359.18114-1-zack@kde.org/ v2: * rename variable 'dev' to 'device' (Javier) Signed-off-by: Thomas Zimmermann Reported-by: Zack Rusin Reviewed-by: Javier Martinez Canillas Reviewed-by: Zack Rusin Reviewed-by: Hans de Goede CC: stable@vger.kernel.org # v5.11+ Link: https://patchwork.freedesktop.org/patch/msgid/20220125091222.21457-2-tzimmermann@suse.de Signed-off-by: Greg Kroah-Hartman

fbdev: fbmem: Fix the implicit type casting

2022-02-03T12:52:03Z

In function do_fb_ioctl(), the "arg" is the type of unsigned long, and in "case FBIOBLANK:" this argument is casted into an int before passig to fb_blank(). In fb_blank(), the comparision if (blank > FB_BLANK_POWERDOWN) would be bypass if the original "arg" is a large number, which is possible because it comes from the user input. Fix this by adding the check before the function call. Reviewed-by: Guenter Roeck Reviewed-by: Sam Ravnborg Acked-by: Helge Deller Signed-off-by: Yizhuo Zhai Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220202235811.1621017-1-yzhai003@ucr.edu

fbdev: fbmem: add a helper to determine if an aperture is used by a fw fb

2021-12-31T13:57:45Z

Add a function for drivers to check if the a firmware initialized fb is corresponds to their aperture. This allows drivers to check if the device corresponds to what the firmware set up as the display device. Bug: https://bugzilla.kernel.org/show_bug.cgi?id=215203 Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1840 Signed-off-by: Alex Deucher

fbdev: fbmem: Fix double free of 'fb_info->pixmap.addr'

2021-10-10T07:50:32Z

savagefb and some other drivers call kfree to free 'info->pixmap.addr' even after calling unregister_framebuffer, which may cause double free. Fix this by setting 'fb_info->pixmap.addr' to NULL after kfree in unregister_framebuffer. The following log reveals it: [ 37.318872] BUG: KASAN: double-free or invalid-free in kfree+0x13e/0x290 [ 37.319369] [ 37.320803] Call Trace: [ 37.320992] dump_stack_lvl+0xa8/0xd1 [ 37.321274] print_address_description+0x87/0x3b0 [ 37.321632] ? kfree+0x13e/0x290 [ 37.321879] ? kfree+0x13e/0x290 [ 37.322126] ? kfree+0x13e/0x290 [ 37.322374] kasan_report_invalid_free+0x58/0x90 [ 37.322724] ____kasan_slab_free+0x123/0x140 [ 37.323049] __kasan_slab_free+0x11/0x20 [ 37.323347] slab_free_freelist_hook+0x81/0x150 [ 37.323689] ? savagefb_remove+0xa1/0xc0 [savagefb] [ 37.324066] kfree+0x13e/0x290 [ 37.324304] savagefb_remove+0xa1/0xc0 [savagefb] [ 37.324655] pci_device_remove+0xa9/0x250 [ 37.324959] ? pci_device_probe+0x7d0/0x7d0 [ 37.325273] device_release_driver_internal+0x4f7/0x7a0 [ 37.325666] driver_detach+0x1e8/0x2c0 [ 37.325952] bus_remove_driver+0x134/0x290 [ 37.326262] ? sysfs_remove_groups+0x97/0xb0 [ 37.326584] driver_unregister+0x77/0xa0 [ 37.326883] pci_unregister_driver+0x2c/0x1c0 [ 37.336124] [ 37.336245] Allocated by task 5465: [ 37.336507] ____kasan_kmalloc+0xb5/0xe0 [ 37.336801] __kasan_kmalloc+0x9/0x10 [ 37.337069] kmem_cache_alloc_trace+0x12b/0x220 [ 37.337405] register_framebuffer+0x3f3/0xa00 [ 37.337731] foo_register_framebuffer+0x3b/0x50 [savagefb] [ 37.338136] [ 37.338255] Freed by task 5475: [ 37.338492] kasan_set_track+0x3d/0x70 [ 37.338774] kasan_set_free_info+0x23/0x40 [ 37.339081] ____kasan_slab_free+0x10b/0x140 [ 37.339399] __kasan_slab_free+0x11/0x20 [ 37.339694] slab_free_freelist_hook+0x81/0x150 [ 37.340034] kfree+0x13e/0x290 [ 37.340267] do_unregister_framebuffer+0x21c/0x3d0 [ 37.340624] unregister_framebuffer+0x23/0x40 [ 37.340950] savagefb_remove+0x45/0xc0 [savagefb] [ 37.341302] pci_device_remove+0xa9/0x250 [ 37.341603] device_release_driver_internal+0x4f7/0x7a0 [ 37.341990] driver_detach+0x1e8/0x2c0 [ 37.342272] bus_remove_driver+0x134/0x290 [ 37.342577] driver_unregister+0x77/0xa0 [ 37.342873] pci_unregister_driver+0x2c/0x1c0 [ 37.343196] cleanup_module+0x15/0x1c [savagefb] [ 37.343543] __se_sys_delete_module+0x398/0x490 [ 37.343881] __x64_sys_delete_module+0x56/0x60 [ 37.344221] do_syscall_64+0x4d/0xc0 [ 37.344492] entry_SYSCALL_64_after_hwframe+0x44/0xae Signed-off-by: Zheyu Ma Signed-off-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/1633848148-29747-1-git-send-email-zheyuma97@gmail.com

fbmem: don't allow too huge resolutions

2021-09-08T16:52:04Z

syzbot is reporting page fault at vga16fb_fillrect() [1], for vga16fb_check_var() is failing to detect multiplication overflow. if (vxres * vyres > maxmem) { vyres = maxmem / vxres; if (vyres < yres) return -ENOMEM; } Since no module would accept too huge resolutions where multiplication overflow happens, let's reject in the common path. Link: https://syzkaller.appspot.com/bug?extid=04168c8063cfdde1db5e [1] Reported-by: syzbot Debugged-by: Randy Dunlap Signed-off-by: Tetsuo Handa Reviewed-by: Geert Uytterhoeven Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/185175d6-227a-7b55-433d-b070929b262c@i-love.sakura.ne.jp

Merge tag 'drm-misc-next-2021-07-22' of git://anongit.freedesktop.org/drm/drm-misc into drm-next

2021-07-23T01:32:43Z

drm-misc-next for v5.15-rc1: UAPI Changes: - Remove sysfs stats for dma-buf attachments, as it causes a performance regression. Previous merge is not in a rc kernel yet, so no userspace regression possible. Cross-subsystem Changes: - Sanitize user input in kyro's viewport ioctl. - Use refcount_t in fb_info->count - Assorted fixes to dma-buf. - Extend x86 efifb handling to all archs. - Fix neofb divide by 0. - Document corpro,gm7123 bridge dt bindings. Core Changes: - Slightly rework drm master handling. - Cleanup vgaarb handling. - Assorted fixes. Driver Changes: - Add support for ws2401 panel. - Assorted fixes to stm, ast, bochs. - Demidlayer ingenic irq. Signed-off-by: Dave Airlie From: Maarten Lankhorst Link: https://patchwork.freedesktop.org/patch/msgid/2d0d2fe8-01fc-e216-c3fd-38db9e69944e@linux.intel.com

fbmem: Convert from atomic_t to refcount_t on fb_info->count

2021-07-19T20:16:35Z

refcount_t type and corresponding API can protect refcounters from accidental underflow and overflow and further use-after-free situations. Signed-off-by: Xiyu Yang Signed-off-by: Xin Tan Signed-off-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/1626674392-55857-1-git-send-email-xiyuyang19@fudan.edu.cn