* [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store @ 2017-12-06 20:20 ` Gustavo A. R. Silva 2017-12-07 1:24 ` Chanwoo Choi 2017-12-07 2:41 ` MyungJoo Ham 0 siblings, 2 replies; 5+ messages in thread From: Gustavo A. R. Silva @ 2017-12-06 20:20 UTC (permalink / raw) To: MyungJoo Ham, Kyungmin Park, Chanwoo Choi Cc: linux-pm, linux-kernel, Gustavo A. R. Silva df->governor is being dereferenced before it is null checked, hence there is a potential null pointer dereference. Notice that df->governor is being null checked at line 1004: if (df->governor) {, which implies it might be null. Fix this by null checking df->governor before dereferencing it. Addresses-Coverity-ID: 1401988 ("Dereference before null check") Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs") Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> --- drivers/devfreq/devfreq.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 78fb496..14fe76b 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -996,7 +996,8 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, if (df->governor == governor) { ret = 0; goto out; - } else if (df->governor->immutable || governor->immutable) { + } else if ((df->governor && df->governor->immutable) || + governor->immutable) { ret = -EINVAL; goto out; } -- 2.7.4 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store 2017-12-06 20:20 ` [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store Gustavo A. R. Silva @ 2017-12-07 1:24 ` Chanwoo Choi 2017-12-07 23:56 ` Gustavo A. R. Silva 2017-12-07 2:41 ` MyungJoo Ham 1 sibling, 1 reply; 5+ messages in thread From: Chanwoo Choi @ 2017-12-07 1:24 UTC (permalink / raw) To: Gustavo A. R. Silva, MyungJoo Ham, Kyungmin Park; +Cc: linux-pm, linux-kernel On 2017년 12월 07일 05:20, Gustavo A. R. Silva wrote: > df->governor is being dereferenced before it is null checked, > hence there is a potential null pointer dereference. > > Notice that df->governor is being null checked at line 1004: > if (df->governor) {, which implies it might be null. > > Fix this by null checking df->governor before dereferencing it. > > Addresses-Coverity-ID: 1401988 ("Dereference before null check") > Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs") > Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> > --- > drivers/devfreq/devfreq.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > index 78fb496..14fe76b 100644 > --- a/drivers/devfreq/devfreq.c > +++ b/drivers/devfreq/devfreq.c > @@ -996,7 +996,8 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, > if (df->governor == governor) { > ret = 0; > goto out; > - } else if (df->governor->immutable || governor->immutable) { > + } else if ((df->governor && df->governor->immutable) || > + governor->immutable) { > ret = -EINVAL; > goto out; > } > Actually, df->governor would be never NULL because devfreq_add_device() initializes the ->governor always. But, governor_store() doesn't know it. So, looks good to me. Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com> -- Best Regards, Chanwoo Choi Samsung Electronics ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store 2017-12-07 1:24 ` Chanwoo Choi @ 2017-12-07 23:56 ` Gustavo A. R. Silva 0 siblings, 0 replies; 5+ messages in thread From: Gustavo A. R. Silva @ 2017-12-07 23:56 UTC (permalink / raw) To: Chanwoo Choi; +Cc: MyungJoo Ham, Kyungmin Park, linux-pm, linux-kernel Hi Chanwoo, Quoting Chanwoo Choi <cw00.choi@samsung.com>: > On 2017년 12월 07일 05:20, Gustavo A. R. Silva wrote: >> df->governor is being dereferenced before it is null checked, >> hence there is a potential null pointer dereference. >> >> Notice that df->governor is being null checked at line 1004: >> if (df->governor) {, which implies it might be null. >> >> Fix this by null checking df->governor before dereferencing it. >> >> Addresses-Coverity-ID: 1401988 ("Dereference before null check") >> Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs") >> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> >> --- >> drivers/devfreq/devfreq.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c >> index 78fb496..14fe76b 100644 >> --- a/drivers/devfreq/devfreq.c >> +++ b/drivers/devfreq/devfreq.c >> @@ -996,7 +996,8 @@ static ssize_t governor_store(struct device >> *dev, struct device_attribute *attr, >> if (df->governor == governor) { >> ret = 0; >> goto out; >> - } else if (df->governor->immutable || governor->immutable) { >> + } else if ((df->governor && df->governor->immutable) || >> + governor->immutable) { >> ret = -EINVAL; >> goto out; >> } >> > > Actually, df->governor would be never NULL because devfreq_add_device() > initializes the ->governor always. But, governor_store() doesn't know it. > I got it. > So, looks good to me. > Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com> > Thank you -- Gustavo A. R. Silva ^ permalink raw reply [flat|nested] 5+ messages in thread
* RE: [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store 2017-12-06 20:20 ` [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store Gustavo A. R. Silva 2017-12-07 1:24 ` Chanwoo Choi @ 2017-12-07 2:41 ` MyungJoo Ham 2017-12-07 23:57 ` Gustavo A. R. Silva 1 sibling, 1 reply; 5+ messages in thread From: MyungJoo Ham @ 2017-12-07 2:41 UTC (permalink / raw) To: Kyungmin Park, Chanwoo Choi Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Gustavo A. R. Silva > df->governor is being dereferenced before it is null checked, > hence there is a potential null pointer dereference. > > Notice that df->governor is being null checked at line 1004: > if (df->governor) {, which implies it might be null. > > Fix this by null checking df->governor before dereferencing it. > > Addresses-Coverity-ID: 1401988 ("Dereference before null check") > Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs") > Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com> Cheers, MyungJoo > --- > drivers/devfreq/devfreq.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > index 78fb496..14fe76b 100644 ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store 2017-12-07 2:41 ` MyungJoo Ham @ 2017-12-07 23:57 ` Gustavo A. R. Silva 0 siblings, 0 replies; 5+ messages in thread From: Gustavo A. R. Silva @ 2017-12-07 23:57 UTC (permalink / raw) To: MyungJoo Ham; +Cc: Kyungmin Park, Chanwoo Choi, linux-pm, linux-kernel Quoting MyungJoo Ham <myungjoo.ham@samsung.com>: >> df->governor is being dereferenced before it is null checked, >> hence there is a potential null pointer dereference. >> >> Notice that df->governor is being null checked at line 1004: >> if (df->governor) {, which implies it might be null. >> >> Fix this by null checking df->governor before dereferencing it. >> >> Addresses-Coverity-ID: 1401988 ("Dereference before null check") >> Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs") >> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> > > Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com> > Thank you, MyungJoo -- Gustavo A. R. Silva ^ permalink raw reply [flat|nested] 5+ messages in thread
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2017-12-06 20:20 ` [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store Gustavo A. R. Silva
2017-12-07 1:24 ` Chanwoo Choi
2017-12-07 23:56 ` Gustavo A. R. Silva
2017-12-07 2:41 ` MyungJoo Ham
2017-12-07 23:57 ` Gustavo A. R. Silva
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