On Mon, Sep 02, 2019 at 12:32:37PM -0700, Guenter Roeck wrote: > On 9/2/19 11:47 AM, Greg KH wrote: > > On Sun, Sep 01, 2019 at 07:08:29AM -0700, Guenter Roeck wrote: > > > On 9/1/19 1:03 AM, Kalle Valo wrote: > > > > Guenter Roeck <linux@xxxxxxxxxxxx> writes: > > > > > > > > > On Mon, Aug 19, 2019 at 06:02:29PM -0400, Hui Peng wrote: > > > > > > `dev` (struct rsi_91x_usbdev *) field of adapter > > > > > > (struct rsi_91x_usbdev *) is allocated and initialized in > > > > > > `rsi_init_usb_interface`. If any error is detected in information > > > > > > read from the device side, `rsi_init_usb_interface` will be > > > > > > freed. However, in the higher level error handling code in > > > > > > `rsi_probe`, if error is detected, `rsi_91x_deinit` is called > > > > > > again, in which `dev` will be freed again, resulting double free. > > > > > > > > > > > > This patch fixes the double free by removing the free operation on > > > > > > `dev` in `rsi_init_usb_interface`, because `rsi_91x_deinit` is also > > > > > > used in `rsi_disconnect`, in that code path, the `dev` field is not > > > > > > (and thus needs to be) freed. > > > > > > > > > > > > This bug was found in v4.19, but is also present in the latest version > > > > > > of kernel. > > > > > > > > > > > > Reported-by: Hui Peng <benquike@xxxxxxxxx> > > > > > > Reported-by: Mathias Payer <mathias.payer@xxxxxxxxxxxxx> > > > > > > Signed-off-by: Hui Peng <benquike@xxxxxxxxx> > > > > > > > > > > FWIW: > > > > > > > > > > Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx> > > > > > > > > > > This patch is listed as fix for CVE-2019-15504, which has a CVSS 2.0 score > > > > > of 10.0 (high) and CVSS 3.0 score of 9.8 (critical). > > > > > > > > A double free in error path is considered as a critical CVE issue? I'm > > > > very curious, why is that? > > > > > > > > > > You'd have to ask the people assigning CVSS scores. However, if the memory > > > was reallocated, that reallocated memory (which is still in use) is freed. > > > Then all kinds of bad things can happen. > > > > Yes, but moving from "bad things _can_ happen" to "bad things happen" in > > an instance like this will be a tough task. It also requires physical > > access to the machine. > > > > Is this correct even with usbip enabled ? Who has usbip enabled anywhere? :) I don't know if usbip can trigger this type of thing, maybe someone needs to test that... thanks, greg k-h
