Hi Arnd, On Wed, Jun 22, 2016 at 2:37 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > When building with CONFIG_UBSAN_SANITIZE_ALL on ARM, I get this > gcc warning for atyfb: > > drivers/video/fbdev/aty/atyfb_base.c: In function 'aty_bl_update_status': > drivers/video/fbdev/aty/atyfb_base.c:167:33: warning: array subscript is above array bounds [-Warray-bounds] > drivers/video/fbdev/aty/atyfb_base.c:152:26: warning: array subscript is above array bounds [-Warray-bounds] > > Apparently the warning is correct and there is indeed an overflow, > which was never caught. I could only reproduce this on ARM and > have opened a bug against the compiler for the lack of warning. > > This patch makes the array larger, so we cover all possible > registers in the LCD controller without an overflow. > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > Link: https://bugs.linaro.org/show_bug.cgi?id=2349 > --- > drivers/video/fbdev/aty/atyfb_base.c | 2 +- > include/video/mach64.h | 1 + > 2 files changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/video/fbdev/aty/atyfb_base.c b/drivers/video/fbdev/aty/atyfb_base.c > index 001d3d871800..36ffba152eab 100644 > --- a/drivers/video/fbdev/aty/atyfb_base.c > +++ b/drivers/video/fbdev/aty/atyfb_base.c > @@ -134,7 +134,7 @@ > > #if defined(CONFIG_PM) || defined(CONFIG_PMAC_BACKLIGHT) || \ > defined (CONFIG_FB_ATY_GENERIC_LCD) || defined(CONFIG_FB_ATY_BACKLIGHT) > -static const u32 lt_lcd_regs[] = { > +static const u32 lt_lcd_regs[LCD_REG_NUM] = { > CNFG_PANEL_LG, > LCD_GEN_CNTL_LG, > DSTN_CONTROL_LG, > diff --git a/include/video/mach64.h b/include/video/mach64.h > index 89e91c0cb737..9f74e9e0aeb8 100644 > --- a/include/video/mach64.h > +++ b/include/video/mach64.h > @@ -1299,6 +1299,7 @@ > #define APC_LUT_KL 0x38 > #define APC_LUT_MN 0x39 > #define APC_LUT_OP 0x3A > +#define LCD_REG_NUM 0x3B /* total number */ > > /* Values in LCD_GEN_CTRL */ > #define CRT_ON 0x00000001ul This doesn't look like the right fix to me. Before, aty_st_lcd(LCD_MISC_CNTL, reg, par) in aty_bl_update_status() wrote into an arbitrary register. With your fix, it will write to register 0, which is IMHO also not OK. I think aty_st_lcd() and aty_ld_lcd() should check whether the index is out of range, perhaps even with a WARN_ON()? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
