[PATCH v2] Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper().

Subsystems: framebuffer layer, the rest

STALE3113d

4 messages, 3 authors, 2018-03-07 · open the first message on its own page

[PATCH v2] Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper().

From: Peter Malone <hidden>
Date: 2018-01-31 14:57:55 

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 <redacted>
---

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

Re: [PATCH v2] Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper().

From: Mathieu Malaterre <hidden>
Date: 2018-01-31 15:49:33 

Hi Peter,

On Wed, Jan 31, 2018 at 3:57 PM, Peter Malone [off-list ref] 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 <redacted>
---
much better :)
quoted hunk
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 <redacted>

Re: [PATCH v2] Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper().

From: Peter Malone <hidden>
Date: 2018-02-04 14:18:12 

Hi folks,

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.

On Wed, Jan 31, 2018 at 10:49 AM, Mathieu Malaterre [off-list ref] wrote:
Hi Peter,

On Wed, Jan 31, 2018 at 3:57 PM, Peter Malone [off-list ref] wrote:
quoted
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 <redacted>
---
much better :)
quoted
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 <redacted>


-- 
Regards,
Peter.

Re: [PATCH v2] Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper().

From: Bartlomiej Zolnierkiewicz <hidden>
Date: 2018-03-07 13:04:02 

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 [off-list ref] wrote:
quoted
Hi Peter,

On Wed, Jan 31, 2018 at 3:57 PM, Peter Malone [off-list ref] wrote:
quoted
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 <redacted>
---
much better :)
quoted
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 <redacted>
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
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