| Message ID | 20220404194402.29974-1-tzimmermann@suse.de |
|---|---|
| State | New |
| Headers | show |
| Series | fbdev: Fix unregistering of framebuffers without device | expand |
On Mon, Apr 04, 2022 at 09:44:02PM +0200, Thomas Zimmermann wrote: > 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 <SF,VEC,EE,ME,IR,DR,RI,LE> 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 <tzimmermann@suse.de> > Fixes: 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal") > Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> > Cc: Zack Rusin <zackr@vmware.com> > Cc: Javier Martinez Canillas <javierm@redhat.com> > Cc: Hans de Goede <hdegoede@redhat.com> > Cc: stable@vger.kernel.org # v5.11+ > Cc: Helge Deller <deller@gmx.de> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > Cc: Sam Ravnborg <sam@ravnborg.org> > Cc: Zheyu Ma <zheyuma97@gmail.com> > Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn> > Cc: Zhen Lei <thunder.leizhen@huawei.com> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Alex Deucher <alexander.deucher@amd.com> > Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> > Cc: Guenter Roeck <linux@roeck-us.net> > Cc: linux-fbdev@vger.kernel.org > Cc: dri-devel@lists.freedesktop.org > Link: https://lore.kernel.org/all/YkHXO6LGHAN0p1pq@debian/ # [1] > --- > drivers/video/fbdev/core/fbmem.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c > index 34d6bb1bf82e..a6bb0e438216 100644 > --- a/drivers/video/fbdev/core/fbmem.c > +++ b/drivers/video/fbdev/core/fbmem.c > @@ -1579,7 +1579,14 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, > * If it's not a platform device, at least print a warning. A > * fix would add code to remove the device from the system. > */ > - if (dev_is_platform(device)) { > + if (!device) { > + /* TODO: Represent each OF framebuffer as its own > + * device in the device hierarchy. For now, offb > + * doesn't have such a device, so unregister the > + * framebuffer as before without warning. > + */ > + do_unregister_framebuffer(registered_fb[i]); Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Might be good to have a fb_info flag for offb and then check in register_framebuffer that everyone else does have a device? Just to make sure we don't have more surprises here ... -Daniel > + } else if (dev_is_platform(device)) { > registered_fb[i]->forced_out = true; > platform_device_unregister(to_platform_device(device)); > } else { > -- > 2.35.1 >
On Mon, Apr 04, 2022 at 09:44:02PM +0200, Thomas Zimmermann wrote: > 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. > <snip> > > Tested with 5.17 on qemu ppc64le emulation. > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > Fixes: 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal") > Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> > Cc: Zack Rusin <zackr@vmware.com> > Cc: Javier Martinez Canillas <javierm@redhat.com> > Cc: Hans de Goede <hdegoede@redhat.com> > Cc: stable@vger.kernel.org # v5.11+ > Cc: Helge Deller <deller@gmx.de> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > Cc: Sam Ravnborg <sam@ravnborg.org> > Cc: Zheyu Ma <zheyuma97@gmail.com> > Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn> > Cc: Zhen Lei <thunder.leizhen@huawei.com> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Alex Deucher <alexander.deucher@amd.com> > Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> > Cc: Guenter Roeck <linux@roeck-us.net> > Cc: linux-fbdev@vger.kernel.org > Cc: dri-devel@lists.freedesktop.org > Link: https://lore.kernel.org/all/YkHXO6LGHAN0p1pq@debian/ # [1] > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> > --- Tested-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk> -- Regards Sudip
Hello Thomas, On 4/4/22 21:44, Thomas Zimmermann wrote: > 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 <SF,VEC,EE,ME,IR,DR,RI,LE> 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. > I believe the assumption that all firmware fb would have an underlying device was a reasonable one and it's a pity that offb doesn't... But that is how things are and your patch is the least intrusive fix. Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Hi Am 05.04.22 um 11:01 schrieb Daniel Vetter: > On Mon, Apr 04, 2022 at 09:44:02PM +0200, Thomas Zimmermann wrote: >> 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 <SF,VEC,EE,ME,IR,DR,RI,LE> 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 <tzimmermann@suse.de> >> Fixes: 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal") >> Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> >> Cc: Zack Rusin <zackr@vmware.com> >> Cc: Javier Martinez Canillas <javierm@redhat.com> >> Cc: Hans de Goede <hdegoede@redhat.com> >> Cc: stable@vger.kernel.org # v5.11+ >> Cc: Helge Deller <deller@gmx.de> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> Cc: Sam Ravnborg <sam@ravnborg.org> >> Cc: Zheyu Ma <zheyuma97@gmail.com> >> Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn> >> Cc: Zhen Lei <thunder.leizhen@huawei.com> >> Cc: Matthew Wilcox <willy@infradead.org> >> Cc: Alex Deucher <alexander.deucher@amd.com> >> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> >> Cc: Guenter Roeck <linux@roeck-us.net> >> Cc: linux-fbdev@vger.kernel.org >> Cc: dri-devel@lists.freedesktop.org >> Link: https://lore.kernel.org/all/YkHXO6LGHAN0p1pq@debian/ # [1] >> --- >> drivers/video/fbdev/core/fbmem.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c >> index 34d6bb1bf82e..a6bb0e438216 100644 >> --- a/drivers/video/fbdev/core/fbmem.c >> +++ b/drivers/video/fbdev/core/fbmem.c >> @@ -1579,7 +1579,14 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, >> * If it's not a platform device, at least print a warning. A >> * fix would add code to remove the device from the system. >> */ >> - if (dev_is_platform(device)) { >> + if (!device) { >> + /* TODO: Represent each OF framebuffer as its own >> + * device in the device hierarchy. For now, offb >> + * doesn't have such a device, so unregister the >> + * framebuffer as before without warning. >> + */ >> + do_unregister_framebuffer(registered_fb[i]); > > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> > > Might be good to have a fb_info flag for offb and then check in > register_framebuffer that everyone else does have a device? Just to make > sure we don't have more surprises here ... That exists already: all generic/firmware drivers are flagged with FBINFO_MISC_FIRMWARE specifically for the purpose of unloading. HW-native fbdev drivers don't have the flags and will never be unloaded. I double-checked and of the generic drivers, (efifb, vesafb, offb, simplefb, vga16) only offb had no device set. Best regards Thomas > -Daniel > > >> + } else if (dev_is_platform(device)) { >> registered_fb[i]->forced_out = true; >> platform_device_unregister(to_platform_device(device)); >> } else { >> -- >> 2.35.1 >> >
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 34d6bb1bf82e..a6bb0e438216 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1579,7 +1579,14 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a, * If it's not a platform device, at least print a warning. A * fix would add code to remove the device from the system. */ - if (dev_is_platform(device)) { + if (!device) { + /* TODO: Represent each OF framebuffer as its own + * device in the device hierarchy. For now, offb + * doesn't have such a device, so unregister the + * framebuffer as before without warning. + */ + do_unregister_framebuffer(registered_fb[i]); + } else if (dev_is_platform(device)) { registered_fb[i]->forced_out = true; platform_device_unregister(to_platform_device(device)); } else {
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 <SF,VEC,EE,ME,IR,DR,RI,LE> 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 <tzimmermann@suse.de> Fixes: 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on forced removal") Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Cc: Zack Rusin <zackr@vmware.com> Cc: Javier Martinez Canillas <javierm@redhat.com> Cc: Hans de Goede <hdegoede@redhat.com> Cc: stable@vger.kernel.org # v5.11+ Cc: Helge Deller <deller@gmx.de> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Zheyu Ma <zheyuma97@gmail.com> Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn> Cc: Zhen Lei <thunder.leizhen@huawei.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Guenter Roeck <linux@roeck-us.net> Cc: linux-fbdev@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Link: https://lore.kernel.org/all/YkHXO6LGHAN0p1pq@debian/ # [1] --- drivers/video/fbdev/core/fbmem.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)