# \[PATCH\] fbdev: remove unnecessary memset in vfb - Subsystems: FRAMEBUFFER LAYER, THE REST - Maintainers: Helge Deller, Linus Torvalds - List: linux-fbdev - 4 messages, 3 authors - Page: https://ratatoskr.run/linux-fbdev/2015/06/4518626/t ## \[PATCH\] fbdev: remove unnecessary memset in vfb - From: Marcin Chojnacki \ - Date: 2015-06-18 13:02:41 - Message: https://ratatoskr.run/linux-fbdev/2015/06/4518626.md ```text In vfb_probe memory is allocated using rvmalloc which automatically sets the allocated memory to zero. This patch removes the second unnecessary memset in vfb_probe. Signed-off-by: Marcin Chojnacki --- drivers/video/fbdev/vfb.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/drivers/video/fbdev/vfb.c b/drivers/video/fbdev/vfb.c index 70a897b..b2d38b7 100644 --- a/drivers/video/fbdev/vfb.c +++ b/drivers/video/fbdev/vfb.c @@ -490,14 +490,6 @@ static int vfb_probe(struct platform_device *dev) if (!(videomemory = rvmalloc(videomemorysize))) return retval; - /* - * VFB must clear memory to prevent kernel info - * leakage into userspace - * VGA-based drivers MUST NOT clear memory if - * they want to be able to take over vgacon - */ - memset(videomemory, 0, videomemorysize); - info = framebuffer_alloc(sizeof(u32) * 256, &dev->dev); if (!info) goto err; -- 2.1.4 ``` ## Re: \[PATCH\] fbdev: remove unnecessary memset in vfb - From: Tomi Valkeinen \ - Date: 2015-08-20 07:56:34 - Message: https://ratatoskr.run/linux-fbdev/2015/08/4560887.md ```text On 18/06/15 16:01, Marcin Chojnacki wrote: > In vfb_probe memory is allocated using rvmalloc which automatically > sets the allocated memory to zero. This patch removes the second > unnecessary memset in vfb_probe. > > Signed-off-by: Marcin Chojnacki > --- > drivers/video/fbdev/vfb.c | 8 -------- > 1 file changed, 8 deletions(-) Thanks, queued for 4.3. Tomi ``` ## Re: \[PATCH\] fbdev: remove unnecessary memset in vfb - From: Geert Uytterhoeven \ - Date: 2015-08-20 08:21:08 - Message: https://ratatoskr.run/linux-fbdev/2015/08/4560909.md ```text On Thu, Jun 18, 2015 at 3:01 PM, Marcin Chojnacki [ref] wrote: > In vfb_probe memory is allocated using rvmalloc which automatically > sets the allocated memory to zero. This patch removes the second > unnecessary memset in vfb_probe. > > Signed-off-by: Marcin Chojnacki > --- > drivers/video/fbdev/vfb.c | 8 -------- > 1 file changed, 8 deletions(-) > > diff --git a/drivers/video/fbdev/vfb.c b/drivers/video/fbdev/vfb.c > index 70a897b..b2d38b7 100644 > --- a/drivers/video/fbdev/vfb.c > +++ b/drivers/video/fbdev/vfb.c > @@ -490,14 +490,6 @@ static int vfb_probe(struct platform_device *dev) > if (!(videomemory = rvmalloc(videomemorysize))) > return retval; > > - /* > - * VFB must clear memory to prevent kernel info > - * leakage into userspace > - * VGA-based drivers MUST NOT clear memory if > - * they want to be able to take over vgacon > - */ > - memset(videomemory, 0, videomemorysize); > - As vfb also serves as a sample driver, I think it would be worthwhile to move the comment to rvmalloc(). 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 ``` ## Re: \[PATCH\] fbdev: remove unnecessary memset in vfb - From: Tomi Valkeinen \ - Date: 2015-08-20 09:05:34 - Message: https://ratatoskr.run/linux-fbdev/2015/08/4560946.md ```text On 20/08/15 11:21, Geert Uytterhoeven wrote: > On Thu, Jun 18, 2015 at 3:01 PM, Marcin Chojnacki [ref] wrote: >> In vfb_probe memory is allocated using rvmalloc which automatically >> sets the allocated memory to zero. This patch removes the second >> unnecessary memset in vfb_probe. >> >> Signed-off-by: Marcin Chojnacki >> --- >> drivers/video/fbdev/vfb.c | 8 -------- >> 1 file changed, 8 deletions(-) >> >> diff --git a/drivers/video/fbdev/vfb.c b/drivers/video/fbdev/vfb.c >> index 70a897b..b2d38b7 100644 >> --- a/drivers/video/fbdev/vfb.c >> +++ b/drivers/video/fbdev/vfb.c >> @@ -490,14 +490,6 @@ static int vfb_probe(struct platform_device *dev) >> if (!(videomemory = rvmalloc(videomemorysize))) >> return retval; >> >> - /* >> - * VFB must clear memory to prevent kernel info >> - * leakage into userspace >> - * VGA-based drivers MUST NOT clear memory if >> - * they want to be able to take over vgacon >> - */ >> - memset(videomemory, 0, videomemorysize); >> - > > As vfb also serves as a sample driver, I think it would be worthwhile to move > the comment to rvmalloc(). I changed the patch as follows: commit c0a3229313d6931a77e0c1e1c22e398c0312bf6f Author: Marcin Chojnacki [ref] Date: Thu Jun 18 15:01:52 2015 +0200 fbdev: remove unnecessary memset in vfb In vfb_probe memory is allocated using rvmalloc which automatically sets the allocated memory to zero. This patch removes the second unnecessary memset in vfb_probe. Signed-off-by: Marcin Chojnacki [ref] Signed-off-by: Tomi Valkeinen [ref] diff --git a/drivers/video/fbdev/vfb.c b/drivers/video/fbdev/vfb.c index 70a897b1e458..b9c2f81fb6b9 100644 --- a/drivers/video/fbdev/vfb.c +++ b/drivers/video/fbdev/vfb.c @@ -51,7 +51,14 @@ static void *rvmalloc(unsigned long size) if (!mem) return NULL; - memset(mem, 0, size); /* Clear the ram out, no junk to the user */ + /* + * VFB must clear memory to prevent kernel info + * leakage into userspace + * VGA-based drivers MUST NOT clear memory if + * they want to be able to take over vgacon + */ + + memset(mem, 0, size); adr = (unsigned long) mem; while (size > 0) { SetPageReserved(vmalloc_to_page((void *)adr)); @@ -490,14 +497,6 @@ static int vfb_probe(struct platform_device *dev) if (!(videomemory = rvmalloc(videomemorysize))) return retval; - /* - * VFB must clear memory to prevent kernel info - * leakage into userspace - * VGA-based drivers MUST NOT clear memory if - * they want to be able to take over vgacon - */ - memset(videomemory, 0, videomemorysize); - info = framebuffer_alloc(sizeof(u32) * 256, &dev->dev); if (!info) goto err; ```