From: Alexander Larkin avlarkin82@gmail.com
commit f8f84af5da9ee04ef1d271528656dac42a090d00 upstream.
Even though we validate user-provided inputs we then traverse past validated data when applying the new map. The issue was originally discovered by Murray McAllister with this simple POC (if the following is executed by an unprivileged user it will instantly panic the system):
int main(void) { int fd, ret; unsigned int buffer[10000];
fd = open("/dev/input/js0", O_RDONLY); if (fd == -1) printf("Error opening file\n");
ret = ioctl(fd, JSIOCSBTNMAP & ~IOCSIZE_MASK, &buffer); printf("%d\n", ret); }
The solution is to traverse internal buffer which is guaranteed to only contain valid date when constructing the map.
Fixes: 182d679b2298 ("Input: joydev - prevent potential read overflow in ioctl") Fixes: 999b874f4aa3 ("Input: joydev - validate axis/button maps before clobbering current ones") Reported-by: Murray McAllister murray.mcallister@gmail.com Suggested-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Alexander Larkin avlarkin82@gmail.com Link: https://lore.kernel.org/r/20210620120030.1513655-1-avlarkin82@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Dmitry Torokhov dmitry.torokhov@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/input/joydev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/input/joydev.c +++ b/drivers/input/joydev.c @@ -492,7 +492,7 @@ static int joydev_handle_JSIOCSBTNMAP(st memcpy(joydev->keypam, keypam, len);
for (i = 0; i < joydev->nkey; i++) - joydev->keymap[keypam[i] - BTN_MISC] = i; + joydev->keymap[joydev->keypam[i] - BTN_MISC] = i;
out: kfree(keypam);