On Tue, May 11, 2021 at 3:40 AM Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > > 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 Thanks Uffe! I modified the patch as suggested and sent as v2. Best, - Tong
