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   1 From foo@baz Mon May 28 08:52:37 CEST 2018
   2 From: Peter Malone <peter.malone@gmail.com>
   3 Date: Wed, 7 Mar 2018 14:00:34 +0100
   4 Subject: fbdev: Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper().
   5
   6 From: Peter Malone <peter.malone@gmail.com>
   7
   8 [ Upstream commit 250c6c49e3b68756b14983c076183568636e2bde ]
   9
  10 Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in
  11 sbusfb_ioctl_helper().
  12
  13 'index' is defined as an int in sbusfb_ioctl_helper().
  14 We retrieve this from the user:
  15 if (get_user(index, &c->index) ||
  16     __get_user(count, &c->count) ||
  17     __get_user(ured, &c->red) ||
  18     __get_user(ugreen, &c->green) ||
  19     __get_user(ublue, &c->blue))
  20        return -EFAULT;
  21
  22 and then we use 'index' in the following way:
  23 red = cmap->red[index + i] >> 8;
  24 green = cmap->green[index + i] >> 8;
  25 blue = cmap->blue[index + i] >> 8;
  26
  27 This is a classic information leak vulnerability. 'index' should be
  28 an unsigned int, given its usage above.
  29
  30 This patch is straight-forward; it changes 'index' to unsigned int
  31 in two switch-cases: FBIOGETCMAP_SPARC && FBIOPUTCMAP_SPARC.
  32
  33 This patch fixes CVE-2018-6412.
  34
  35 Signed-off-by: Peter Malone <peter.malone@gmail.com>
  36 Acked-by: Mathieu Malaterre <malat@debian.org>
  37 Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
  38 Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
  39 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  40 ---
  41  drivers/video/fbdev/sbuslib.c |    4 ++--
  42  1 file changed, 2 insertions(+), 2 deletions(-)
  43
  44 --- a/drivers/video/fbdev/sbuslib.c
  45 +++ b/drivers/video/fbdev/sbuslib.c
  46 @@ -121,7 +121,7 @@ int sbusfb_ioctl_helper(unsigned long cm
  47                 unsigned char __user *ured;
  48                 unsigned char __user *ugreen;
  49                 unsigned char __user *ublue;
  50 -               int index, count, i;
  51 +               unsigned int index, count, i;
  52
  53                 if (get_user(index, &c->index) ||
  54                     __get_user(count, &c->count) ||
  55 @@ -160,7 +160,7 @@ int sbusfb_ioctl_helper(unsigned long cm
  56                 unsigned char __user *ugreen;
  57                 unsigned char __user *ublue;
  58                 struct fb_cmap *cmap = &info->cmap;
  59 -               int index, count, i;
  60 +               unsigned int index, count, i;
  61                 u8 red, green, blue;
  62
  63                 if (get_user(index, &c->index) ||