[PATCH 4.9 015/240] fbdev: zero-fill colormap in fbcmap.c

Greg Kroah-Hartman
2021-05-20T11:02:28Z

From: Phillip Potter <phil@philpotter.co.uk>

commit 19ab233989d0f7ab1de19a036e247afa4a0a1e9c upstream.

Use kzalloc() rather than kmalloc() for the dynamically allocated parts
of the colormap in fb_alloc_cmap_gfp, to prevent a leak of random kernel
data to userspace under certain circumstances.

Fixes a KMSAN-found infoleak bug reported by syzbot at:
https://syzkaller.appspot.com/bug?id=741578659feabd108ad9e06696f0c1f2e69c4b6e

Reported-by: syzbot+47fa9c9c648b765305b9@syzkaller.appspotmail.com
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
Link: https://lore.kernel.org/r/20210331220719.1499743-1-phil@philpotter.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/video/fbdev/core/fbcmap.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/video/fbdev/core/fbcmap.c
+++ b/drivers/video/fbdev/core/fbcmap.c
@@ -101,17 +101,17 @@ int fb_alloc_cmap_gfp(struct fb_cmap *cm
if (!len)
return 0;

- cmap->red = kmalloc(size, flags);
+ cmap->red = kzalloc(size, flags);
if (!cmap->red)
goto fail;
- cmap->green = kmalloc(size, flags);
+ cmap->green = kzalloc(size, flags);
if (!cmap->green)
goto fail;
- cmap->blue = kmalloc(size, flags);
+ cmap->blue = kzalloc(size, flags);
if (!cmap->blue)
goto fail;
if (transp) {
- cmap->transp = kmalloc(size, flags);
+ cmap->transp = kzalloc(size, flags);
if (!cmap->transp)
goto fail;
} else {