On Sun, 9 May 2021 at 23:54, Tong Zhang <ztong0001@xxxxxxxxx> wrote: > > This patch fixes the following issues: > 1. memstick_free_host() will free the host, so the use of ms_dev(host) after > it will be a problem. To fix this, move memstick_free_host() after when we > are done with ms_dev(host). > 2. if something bad happens in memstick_add_host() and we end up taking > err_out in rtsx_usb_ms_drv_probe(), we'd better avoid running rtsx_usb_ms_drv_remove() If the ->probe() function returns a negative error code, the driver core will not invoke the corresponding ->remove() callback. Looks like you may want to double check that ->probe() doesn't return 0, even in case of failure. > 3. In rtsx_usb_ms_drv_remove(), pm need to be disabled before we remove > and free host otherwise memstick_check will be called and UAF will > happen. > > [ 11.351173] BUG: KASAN: use-after-free in rtsx_usb_ms_drv_remove+0x94/0x140 [rtsx_usb_ms] > [ 11.357077] rtsx_usb_ms_drv_remove+0x94/0x140 [rtsx_usb_ms] > [ 11.357376] platform_remove+0x2a/0x50 > [ 11.367531] Freed by task 298: > [ 11.368537] kfree+0xa4/0x2a0 > [ 11.368711] device_release+0x51/0xe0 > [ 11.368905] kobject_put+0xa2/0x120 > [ 11.369090] rtsx_usb_ms_drv_remove+0x8c/0x140 [rtsx_usb_ms] > [ 11.369386] platform_remove+0x2a/0x50 > > [ 12.038408] BUG: KASAN: use-after-free in __mutex_lock.isra.0+0x3ec/0x7c0 > [ 12.045432] mutex_lock+0xc9/0xd0 > [ 12.046080] memstick_check+0x6a/0x578 [memstick] > [ 12.046509] process_one_work+0x46d/0x750 > [ 12.052107] Freed by task 297: > [ 12.053115] kfree+0xa4/0x2a0 > [ 12.053272] device_release+0x51/0xe0 > [ 12.053463] kobject_put+0xa2/0x120 > [ 12.053647] rtsx_usb_ms_drv_remove+0xc4/0x140 [rtsx_usb_ms] > [ 12.053939] platform_remove+0x2a/0x50 > > Signed-off-by: Tong Zhang <ztong0001@xxxxxxxxx> > --- > drivers/memstick/host/rtsx_usb_ms.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/drivers/memstick/host/rtsx_usb_ms.c b/drivers/memstick/host/rtsx_usb_ms.c > index 102dbb8080da..851643d007b7 100644 > --- a/drivers/memstick/host/rtsx_usb_ms.c > +++ b/drivers/memstick/host/rtsx_usb_ms.c > @@ -799,9 +799,10 @@ static int rtsx_usb_ms_drv_probe(struct platform_device *pdev) > > return 0; > err_out: > - memstick_free_host(msh); > pm_runtime_disable(ms_dev(host)); > pm_runtime_put_noidle(ms_dev(host)); > + memstick_free_host(msh); > + platform_set_drvdata(pdev, NULL); > return err; > } > > @@ -811,6 +812,8 @@ static int rtsx_usb_ms_drv_remove(struct platform_device *pdev) > struct memstick_host *msh = host->msh; > int err; > > + if (!host) > + return 0; According to my comment above. You should not reach this point, unless ->probe() was successful and returned 0. > host->eject = true; > cancel_work_sync(&host->handle_req); > > @@ -828,9 +831,6 @@ static int rtsx_usb_ms_drv_remove(struct platform_device *pdev) > } > mutex_unlock(&host->host_mutex); > > - memstick_remove_host(msh); > - memstick_free_host(msh); > - > /* Balance possible unbalanced usage count > * e.g. unconditional module removal > */ > @@ -838,10 +838,11 @@ static int rtsx_usb_ms_drv_remove(struct platform_device *pdev) > pm_runtime_put(ms_dev(host)); > > pm_runtime_disable(ms_dev(host)); > - platform_set_drvdata(pdev, NULL); > - > + memstick_remove_host(msh); > dev_dbg(ms_dev(host), > ": Realtek USB Memstick controller has been removed\n"); > + memstick_free_host(msh); > + platform_set_drvdata(pdev, NULL); > > return 0; > } > -- > 2.25.1 > Besides the above, the change looks reasonable to me. Kind regards Uffe
