| Message ID | 7c560c92-40a7-944a-f46d-28503ce8583c@omp.ru (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] usb: host: xhci-plat: fix possible kernel oops while resuming | expand |
On 6/30/23 11:48 PM, Sergey Shtylyov wrote: > If this driver enables the xHC clocks while resuming from sleep, it calls > clk_prepare_enable() without checking for errors and blithely goes on to > read/write the xHC's registers -- which, with the xHC not being clocked, > at least on ARM32 usually causes an imprecise external abort exceptions > which cause kernel oops. Currently, the chips for which the driver does > the clock dance on suspend/resume seem to be the Broadcom STB SoCs, based > on ARM32 CPUs, as it seems... > > Found by Linux Verification Center (linuxtesting.org) with the Svace static > analysis tool. > > Fixes: 8bd954c56197 ("usb: host: xhci-plat: suspend and resume clocks") > Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru> > > --- > This patch is against the 'usb-linus' branch of Greg KH's 'usb.git' repo... > > Changes in version 2: > - fixed up the error path for clk_prepare_enable() calls in xhci_plat_resume(). Scratch that, still not correct enough... > drivers/usb/host/xhci-plat.c | 21 +++++++++++++++++---- > 1 file changed, 17 insertions(+), 4 deletions(-) > > Index: usb/drivers/usb/host/xhci-plat.c > =================================================================== > --- usb.orig/drivers/usb/host/xhci-plat.c > +++ usb/drivers/usb/host/xhci-plat.c > @@ -470,23 +470,36 @@ static int __maybe_unused xhci_plat_resu > int ret; > > if (!device_may_wakeup(dev) && (xhci->quirks & XHCI_SUSPEND_RESUME_CLKS)) { > - clk_prepare_enable(xhci->clk); > - clk_prepare_enable(xhci->reg_clk); > + ret = clk_prepare_enable(xhci->clk); > + if (ret) > + return ret; > + > + ret = clk_prepare_enable(xhci->reg_clk); > + if (ret) > + goto disable_clk; > } > > ret = xhci_priv_resume_quirk(hcd); > if (ret) > - return ret; > + goto disable_reg_clk; > > ret = xhci_resume(xhci, 0); > if (ret) > - return ret; > + goto disable_reg_clk; > > pm_runtime_disable(dev); > pm_runtime_set_active(dev); > pm_runtime_enable(dev); > > return 0; > + > +disable_reg_clk: > + clk_disable_unprepare(xhci->reg_clk); > + > +disable_clk: > + clk_disable_unprepare(xhci->clk); > + > + return ret; > } [...] Grr, the error path is still incorrect here -- it should've checked xhci->quirks/etc. before calling the clock disable/unprepare... :-( MBR, Sergey
Index: usb/drivers/usb/host/xhci-plat.c =================================================================== --- usb.orig/drivers/usb/host/xhci-plat.c +++ usb/drivers/usb/host/xhci-plat.c @@ -470,23 +470,36 @@ static int __maybe_unused xhci_plat_resu int ret; if (!device_may_wakeup(dev) && (xhci->quirks & XHCI_SUSPEND_RESUME_CLKS)) { - clk_prepare_enable(xhci->clk); - clk_prepare_enable(xhci->reg_clk); + ret = clk_prepare_enable(xhci->clk); + if (ret) + return ret; + + ret = clk_prepare_enable(xhci->reg_clk); + if (ret) + goto disable_clk; } ret = xhci_priv_resume_quirk(hcd); if (ret) - return ret; + goto disable_reg_clk; ret = xhci_resume(xhci, 0); if (ret) - return ret; + goto disable_reg_clk; pm_runtime_disable(dev); pm_runtime_set_active(dev); pm_runtime_enable(dev); return 0; + +disable_reg_clk: + clk_disable_unprepare(xhci->reg_clk); + +disable_clk: + clk_disable_unprepare(xhci->clk); + + return ret; } static int __maybe_unused xhci_plat_runtime_suspend(struct device *dev)
If this driver enables the xHC clocks while resuming from sleep, it calls clk_prepare_enable() without checking for errors and blithely goes on to read/write the xHC's registers -- which, with the xHC not being clocked, at least on ARM32 usually causes an imprecise external abort exceptions which cause kernel oops. Currently, the chips for which the driver does the clock dance on suspend/resume seem to be the Broadcom STB SoCs, based on ARM32 CPUs, as it seems... Found by Linux Verification Center (linuxtesting.org) with the Svace static analysis tool. Fixes: 8bd954c56197 ("usb: host: xhci-plat: suspend and resume clocks") Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru> --- This patch is against the 'usb-linus' branch of Greg KH's 'usb.git' repo... Changes in version 2: - fixed up the error path for clk_prepare_enable() calls in xhci_plat_resume(). drivers/usb/host/xhci-plat.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-)