On Sat, Jul 03, 2021 at 02:20:13PM +0300, Denis Efremov wrote:

Hi,

CVE-2021-3612 was assigned to this patch.


On 2/17/21 9:10 AM, Dan Carpenter wrote:

quoted

The problem here is that "len" might be less than "joydev->nabs" so the
loops which verfy abspam[i] and keypam[] might read beyond the buffer.

The added check looks insufficient to me. There are second loops in these
functions with unpatched "i < joydev->nabs;" and "i < joydev->nkey;" checks.

Thanks, Denis.

You're right.  The fix isn't complete.  We discussed this in a different
thread but I sort of assumed it was dealt with and didn't follow up.  :/

https://lore.kernel.org/lkml/20210620120030.1513655-1-avlarkin82@gmail.com/ (local)

regards,
dan carpenter

quoted

Fixes: 999b874f4aa3 ("Input: joydev - validate axis/button maps before clobbering current ones")
Signed-off-by: Dan Carpenter <redacted>
---
 drivers/input/joydev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/input/joydev.c b/drivers/input/joydev.c
index a2b5fbba2d3b..750f4513fe20 100644
--- a/drivers/input/joydev.c
+++ b/drivers/input/joydev.c

@@ -456,7 +456,7 @@ static int joydev_handle_JSIOCSAXMAP(struct joydev *joydev,
 	if (IS_ERR(abspam))
 		return PTR_ERR(abspam);
 
-	for (i = 0; i < joydev->nabs; i++) {
+	for (i = 0; i < len && i < joydev->nabs; i++) {
 		if (abspam[i] > ABS_MAX) {
 			retval = -EINVAL;
 			goto out;

        memcpy(joydev->abspam, abspam, len);

        for (i = 0; i < joydev->nabs; i++) // <== HERE
                joydev->absmap[joydev->abspam[i]] = i;

quoted

@@ -487,7 +487,7 @@ static int joydev_handle_JSIOCSBTNMAP(struct joydev *joydev,
 	if (IS_ERR(keypam))
 		return PTR_ERR(keypam);
 
-	for (i = 0; i < joydev->nkey; i++) {
+	for (i = 0; i < (len / 2) && i < joydev->nkey; i++) {
 		if (keypam[i] > KEY_MAX || keypam[i] < BTN_MISC) {
 			retval = -EINVAL;
 			goto out;

        memcpy(joydev->keypam, keypam, len);

        for (i = 0; i < joydev->nkey; i++) // <== HERE
                joydev->keymap[keypam[i] - BTN_MISC] = i;


Also at the beginning of joydev_handle_JSIOCSAXMAP() there is a
	len = min(len, sizeof(joydev->abspam));
	abspam = memdup_user(argp, len);

Maybe we can call min(len, joydev->nabs) instead or even min3() and
use only len in the for loops then? Same for joydev_handle_JSIOCSBTNMAP.

Thanks,
Denis