| Message ID | 1387549460-18501-1-git-send-email-bigeasy@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Dec 20, 2013 at 3:24 PM, Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote: > If the primary GPU driver has been loaded _after_ system as a module > then this logo memory is no longer valid. > Managed to crash the system by booting a box without a GPU and then > hotpluggin => BOOM. Which GPU driver is this? drivers/video/fbmem.c:fb_prepare_logo() has protection against this: if (info->flags & FBINFO_MISC_TILEBLITTING || info->flags & FBINFO_MODULE) return 0; > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > drivers/video/logo/logo.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/video/logo/logo.c b/drivers/video/logo/logo.c > index 080c35b..a26bb16 100644 > --- a/drivers/video/logo/logo.c > +++ b/drivers/video/logo/logo.c > @@ -36,6 +36,9 @@ const struct linux_logo * __init_refok fb_find_logo(int depth) > if (nologo) > return NULL; > > + if (system_state != SYSTEM_BOOTING) > + return NULL; > + > if (depth >= 1) { > #ifdef CONFIG_LOGO_LINUX_MONO > /* Generic Linux logo */ Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 12/20/2013 04:27 PM, Geert Uytterhoeven wrote: > On Fri, Dec 20, 2013 at 3:24 PM, Sebastian Andrzej Siewior > <bigeasy@linutronix.de> wrote: >> If the primary GPU driver has been loaded _after_ system as a module >> then this logo memory is no longer valid. >> Managed to crash the system by booting a box without a GPU and then >> hotpluggin => BOOM. > > Which GPU driver is this? i915. > > drivers/video/fbmem.c:fb_prepare_logo() has protection against this: > > if (info->flags & FBINFO_MISC_TILEBLITTING || > info->flags & FBINFO_MODULE) > return 0; but gpu driver is built-in. I just add PCI device at run-time. The same thing should happen if you go to sysfs and remove the PCI device and then do echo 1 > /sys/bus/pci/rescan Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 12/20/2013 04:31 PM, Sebastian Andrzej Siewior wrote: > On 12/20/2013 04:27 PM, Geert Uytterhoeven wrote: >> On Fri, Dec 20, 2013 at 3:24 PM, Sebastian Andrzej Siewior >> <bigeasy@linutronix.de> wrote: >>> If the primary GPU driver has been loaded _after_ system as a module >>> then this logo memory is no longer valid. >>> Managed to crash the system by booting a box without a GPU and then >>> hotpluggin => BOOM. >> >> drivers/video/fbmem.c:fb_prepare_logo() has protection against this: >> >> if (info->flags & FBINFO_MISC_TILEBLITTING || >> info->flags & FBINFO_MODULE) >> return 0; > > but gpu driver is built-in. I just add PCI device at run-time. The same > thing should happen if you go to sysfs and remove the PCI device and > then do No I see where you are going with this. My description of the problem is wrong. The problem is nothing to do with the driver being a module. If nobody objects this or suggests a different solution then I'm going to provide a patch with a proper description. Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Dec 20, 2013 at 4:49 PM, Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote: > On 12/20/2013 04:31 PM, Sebastian Andrzej Siewior wrote: >> On 12/20/2013 04:27 PM, Geert Uytterhoeven wrote: >>> On Fri, Dec 20, 2013 at 3:24 PM, Sebastian Andrzej Siewior >>> <bigeasy@linutronix.de> wrote: >>>> If the primary GPU driver has been loaded _after_ system as a module >>>> then this logo memory is no longer valid. >>>> Managed to crash the system by booting a box without a GPU and then >>>> hotpluggin => BOOM. >>> >>> drivers/video/fbmem.c:fb_prepare_logo() has protection against this: >>> >>> if (info->flags & FBINFO_MISC_TILEBLITTING || >>> info->flags & FBINFO_MODULE) >>> return 0; >> >> but gpu driver is built-in. I just add PCI device at run-time. The same >> thing should happen if you go to sysfs and remove the PCI device and >> then do > > No I see where you are going with this. My description of the problem > is wrong. The problem is nothing to do with the driver being a module. Yes, I got confused by the "as a module". > If nobody objects this or suggests a different solution then I'm going > to provide a patch with a proper description. Is "system_state != SYSTEM_BOOTING" the right check? How long is is in the SYSTEM_BOOTING state? Ah, kernel_init() does: free_initmem(); mark_rodata_ro(); system_state = SYSTEM_RUNNING; So this looks OK to me. We used to have an initmem_freed flag, but it was removed 15 years ago. 11 years ago, we got system_state, for the same purpose ;-) Looking at commit 70802c60379fb843c485dfd4cab9e8f527d8fe81 Author: Antonino A. Daplas <adaplas@gmail.com> Date: Tue May 8 00:38:14 2007 -0700 fbdev: don't show logo if driver or fbcon are modular it seems we were not aware of the existence of system_state.... I guess you can remove FBINFO_MODULE after your fix? BTW, I'm wondering if modprobing newport_con.ko crashes, too, as it seems to call fb_find_logo() without any protection. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/video/logo/logo.c b/drivers/video/logo/logo.c index 080c35b..a26bb16 100644 --- a/drivers/video/logo/logo.c +++ b/drivers/video/logo/logo.c @@ -36,6 +36,9 @@ const struct linux_logo * __init_refok fb_find_logo(int depth) if (nologo) return NULL; + if (system_state != SYSTEM_BOOTING) + return NULL; + if (depth >= 1) { #ifdef CONFIG_LOGO_LINUX_MONO /* Generic Linux logo */
If the primary GPU driver has been loaded _after_ system as a module then this logo memory is no longer valid. Managed to crash the system by booting a box without a GPU and then hotpluggin => BOOM. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/video/logo/logo.c | 3 +++ 1 file changed, 3 insertions(+)