4.14-stable review patch. If anyone has any objections, please let me know.
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From: Peter Malone peter.malone@gmail.com
[ 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@gmail.com Acked-by: Mathieu Malaterre malat@debian.org Signed-off-by: Bartlomiej Zolnierkiewicz b.zolnierkie@samsung.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -122,7 +122,7 @@ 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) || @@ -161,7 +161,7 @@ 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) ||