3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Malone <peter.malone@xxxxxxxxx> [ Upstream commit 250c6c49e3b68756b14983c076183568636e2bde ] Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper(). 'index' is defined as an int in sbusfb_ioctl_helper(). We retrieve this from the user: if (get_user(index, &c->index) || __get_user(count, &c->count) || __get_user(ured, &c->red) || __get_user(ugreen, &c->green) || __get_user(ublue, &c->blue)) return -EFAULT; and then we use 'index' in the following way: red = cmap->red[index + i] >> 8; green = cmap->green[index + i] >> 8; blue = cmap->blue[index + i] >> 8; This is a classic information leak vulnerability. 'index' should be an unsigned int, given its usage above. This patch is straight-forward; it changes 'index' to unsigned int in two switch-cases: FBIOGETCMAP_SPARC && FBIOPUTCMAP_SPARC. This patch fixes CVE-2018-6412. Signed-off-by: Peter Malone <peter.malone@xxxxxxxxx> Acked-by: Mathieu Malaterre <malat@xxxxxxxxxx> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/video/fbdev/sbuslib.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/video/fbdev/sbuslib.c +++ b/drivers/video/fbdev/sbuslib.c @@ -121,7 +121,7 @@ int sbusfb_ioctl_helper(unsigned long cm unsigned char __user *ured; unsigned char __user *ugreen; unsigned char __user *ublue; - int index, count, i; + unsigned int index, count, i; if (get_user(index, &c->index) || __get_user(count, &c->count) || @@ -160,7 +160,7 @@ int sbusfb_ioctl_helper(unsigned long cm unsigned char __user *ugreen; unsigned char __user *ublue; struct fb_cmap *cmap = &info->cmap; - int index, count, i; + unsigned int index, count, i; u8 red, green, blue; if (get_user(index, &c->index) ||