Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH] intel_idle: avoid theoretical uninitialized data usage | Date | Mon, 14 Nov 2016 01:29:47 +0100 |
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On Monday, October 24, 2016 05:52:37 PM Arnd Bergmann wrote: > When CONFIG_PCI is disabled, pci_read_config_byte() may not update > its result, as indicated by this warning: > > drivers/idle/i7300_idle.c: In function ‘i7300_idle_notifier’: > drivers/idle/i7300_idle.c:423:141: warning: ‘got_ctl’ may be used uninitialized in this function [-Wmaybe-uninitialized] > drivers/idle/i7300_idle.c:415:5: note: ‘got_ctl’ was declared here > > We know the function is never called if CONFIG_PCI is not set, so > this is harmless, but we can avoid the problem by checking the > return value of the config space accessor before using the result. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/idle/i7300_idle.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/idle/i7300_idle.c b/drivers/idle/i7300_idle.c > index ffeebc7e9f1c..9a104e558c77 100644 > --- a/drivers/idle/i7300_idle.c > +++ b/drivers/idle/i7300_idle.c > @@ -347,6 +347,7 @@ static int i7300_idle_thrt_save(void) > { > u32 new_mc_val; > u8 gblactlm; > + int ret; > > pci_read_config_byte(fbd_dev, DIMM_THRTCTL, &i7300_idle_thrtctl_saved); > pci_read_config_byte(fbd_dev, DIMM_THRTLOW, &i7300_idle_thrtlow_saved); > @@ -364,7 +365,9 @@ static int i7300_idle_thrt_save(void) > * unlimited-activations while in open-loop throttling (i.e., when > * Global Activation Throttle Limit is zero). > */ > - pci_read_config_byte(fbd_dev, DIMM_GBLACT, &gblactlm); > + ret = pci_read_config_byte(fbd_dev, DIMM_GBLACT, &gblactlm); > + if (ret) > + return ret; > dprintk("thrtctl_saved = 0x%02x, thrtlow_saved = 0x%02x\n", > i7300_idle_thrtctl_saved, > i7300_idle_thrtlow_saved); > @@ -413,14 +416,16 @@ static void i7300_idle_stop(void) > { > u8 new_ctl; > u8 got_ctl; > + int ret; > > new_ctl = i7300_idle_thrtctl_saved & ~DIMM_THRTCTL_THRMHUNT; > pci_write_config_byte(fbd_dev, DIMM_THRTCTL, new_ctl); > > pci_write_config_byte(fbd_dev, DIMM_THRTLOW, i7300_idle_thrtlow_saved); > pci_write_config_byte(fbd_dev, DIMM_THRTCTL, i7300_idle_thrtctl_saved); > - pci_read_config_byte(fbd_dev, DIMM_THRTCTL, &got_ctl); > - WARN_ON_ONCE(got_ctl != i7300_idle_thrtctl_saved); > + ret = pci_read_config_byte(fbd_dev, DIMM_THRTCTL, &got_ctl); > + > + WARN_ON_ONCE(ret || (got_ctl != i7300_idle_thrtctl_saved)); > } >
Applied (with a minor subject tweak).
Thanks, Rafael
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