In dw_mci_runtime_resume() 'host->slot' could be null, but check is not cover all corresponding code.
Fix this bug by changing check place.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: 4a835afd808a (mmc: dw_mmc: Fix potential null pointer risk)
Signed-off-by: Aleksandr Mishin <[email protected]>
---
drivers/mmc/host/dw_mmc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 829af2c98a44..a4f124452abc 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -3570,8 +3570,10 @@ int dw_mci_runtime_resume(struct device *dev)
DW_MCI_ERROR_FLAGS);
mci_writel(host, CTRL, SDMMC_CTRL_INT_ENABLE);
+ if (!host->slot)
+ goto err;
- if (host->slot && host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
+ if (host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
dw_mci_set_ios(host->slot->mmc, &host->slot->mmc->ios);
/* Force setup bus to guarantee available clock output */
--
2.30.2
On Thu, 7 Mar 2024 at 09:53, Aleksandr Mishin <[email protected]> wrote:
>
> In dw_mci_runtime_resume() 'host->slot' could be null, but check is not cover all corresponding code.
> Fix this bug by changing check place.
In fact host->slot can never be NULL in dw_mci_runtime_resume() or in
dw_mci_runtime_suspend().
A better fix would thus be to remove the redundant checks.
Kind regards
Uffe
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 4a835afd808a (mmc: dw_mmc: Fix potential null pointer risk)
> Signed-off-by: Aleksandr Mishin <[email protected]>
> ---
> drivers/mmc/host/dw_mmc.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 829af2c98a44..a4f124452abc 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -3570,8 +3570,10 @@ int dw_mci_runtime_resume(struct device *dev)
> DW_MCI_ERROR_FLAGS);
> mci_writel(host, CTRL, SDMMC_CTRL_INT_ENABLE);
>
> + if (!host->slot)
> + goto err;
>
> - if (host->slot && host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
> + if (host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
> dw_mci_set_ios(host->slot->mmc, &host->slot->mmc->ios);
>
> /* Force setup bus to guarantee available clock output */
> --
> 2.30.2
>
>
07.03.2024 13:57, Ulf Hansson wrote:
> On Thu, 7 Mar 2024 at 09:53, Aleksandr Mishin <[email protected]> wrote:
>>
>> In dw_mci_runtime_resume() 'host->slot' could be null, but check is not cover all corresponding code.
>> Fix this bug by changing check place.
>
> In fact host->slot can never be NULL in dw_mci_runtime_resume() or in
> dw_mci_runtime_suspend().
>
> A better fix would thus be to remove the redundant checks.
>
> Kind regards
> Uffe
>
>>
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>
>> Fixes: 4a835afd808a (mmc: dw_mmc: Fix potential null pointer risk)
>> Signed-off-by: Aleksandr Mishin <[email protected]>
>> ---
>> drivers/mmc/host/dw_mmc.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 829af2c98a44..a4f124452abc 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -3570,8 +3570,10 @@ int dw_mci_runtime_resume(struct device *dev)
>> DW_MCI_ERROR_FLAGS);
>> mci_writel(host, CTRL, SDMMC_CTRL_INT_ENABLE);
>>
>> + if (!host->slot)
>> + goto err;
>>
>> - if (host->slot && host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
>> + if (host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
>> dw_mci_set_ios(host->slot->mmc, &host->slot->mmc->ios);
>>
>> /* Force setup bus to guarantee available clock output */
>> --
>> 2.30.2
>>
>>
>
At the same time there are few checks such as "if (host->slot)" in
dw_mci_runtime_resume() and commit
4a835afd808a3dbbac44bb399a902b822dc7445c message contains: "we
previously assumed 'host->slot' could be null, null pointer judgment
should be added" and replaces "if (host->slot->mmc->pm_flags &
MMC_PM_KEEP_POWER)" with "if (host->slot && host->slot->mmc->pm_flags &
MMC_PM_KEEP_POWER)"
So where is the truth?
--
Kind regadrds
Aleksandr
On Thu, 7 Mar 2024 at 20:07, Aleksandr Mishin <[email protected]> wrote:
>
>
>
> 07.03.2024 13:57, Ulf Hansson wrote:
> > On Thu, 7 Mar 2024 at 09:53, Aleksandr Mishin <[email protected]> wrote:
> >>
> >> In dw_mci_runtime_resume() 'host->slot' could be null, but check is not cover all corresponding code.
> >> Fix this bug by changing check place.
> >
> > In fact host->slot can never be NULL in dw_mci_runtime_resume() or in
> > dw_mci_runtime_suspend().
> >
> > A better fix would thus be to remove the redundant checks.
> >
> > Kind regards
> > Uffe
> >
> >>
> >> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> >>
> >> Fixes: 4a835afd808a (mmc: dw_mmc: Fix potential null pointer risk)
> >> Signed-off-by: Aleksandr Mishin <[email protected]>
> >> ---
> >> drivers/mmc/host/dw_mmc.c | 4 +++-
> >> 1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> >> index 829af2c98a44..a4f124452abc 100644
> >> --- a/drivers/mmc/host/dw_mmc.c
> >> +++ b/drivers/mmc/host/dw_mmc.c
> >> @@ -3570,8 +3570,10 @@ int dw_mci_runtime_resume(struct device *dev)
> >> DW_MCI_ERROR_FLAGS);
> >> mci_writel(host, CTRL, SDMMC_CTRL_INT_ENABLE);
> >>
> >> + if (!host->slot)
> >> + goto err;
> >>
> >> - if (host->slot && host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
> >> + if (host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
> >> dw_mci_set_ios(host->slot->mmc, &host->slot->mmc->ios);
> >>
> >> /* Force setup bus to guarantee available clock output */
> >> --
> >> 2.30.2
> >>
> >>
> >
>
> At the same time there are few checks such as "if (host->slot)" in
> dw_mci_runtime_resume() and commit
> 4a835afd808a3dbbac44bb399a902b822dc7445c message contains: "we
> previously assumed 'host->slot' could be null, null pointer judgment
> should be added" and replaces "if (host->slot->mmc->pm_flags &
> MMC_PM_KEEP_POWER)" with "if (host->slot && host->slot->mmc->pm_flags &
> MMC_PM_KEEP_POWER)"
> So where is the truth?
It looks to me that the runtime PM callbacks are prevented from being
called, unless we have a host->slot assigned.
Just adding checks because it looks like the code could need it, isn't
always the correct thing to do. I would rather try to remove the
checks altogether and give it some tests to see how it plays.
Kind regards
Uffe