On Sunday, February 04, 2018 09:18:03 AM Peter Malone wrote:

Hi folks,

Hi,

CVE-2018-6412 has been created for this. Is it possible for you to add a note indicating the CVE number when merging the patch?

I received the CVE number after the patch was created and ack'd, which is why I didn't include it in the commit message.

I queued the patch (with Mathieu's ACK and CVE number added to the patch description) for v4.16, thanks.

On Wed, Jan 31, 2018 at 10:49 AM, Mathieu Malaterre malat@debian.org wrote:

...

Hi Peter,

On Wed, Jan 31, 2018 at 3:57 PM, Peter Malone peter.malone@gmail.com wrote:

...

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.

Signed-off-by: Peter Malone peter.malone@gmail.com

much better :)

...

v2: fixed formatting

drivers/video/fbdev/sbuslib.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/sbuslib.c b/drivers/video/fbdev/sbuslib.c index af6fc97f4ba4..a436d44f1b7f 100644 --- a/drivers/video/fbdev/sbuslib.c +++ b/drivers/video/fbdev/sbuslib.c @@ -122,7 +122,7 @@ int sbusfb_ioctl_helper(unsigned long cmd, unsigned long arg, 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 cmd, unsigned long arg, 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) ||
  

-- 2.14.3

By just looking at the code and commit message:

Acked-by: Mathieu Malaterre malat@debian.org

Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics