diff mbox

[3/5] bfq: Check kstrtoul() return value

Message ID 20170830184211.12471-4-bart.vanassche@wdc.com (mailing list archive)
State New, archived
Headers show

Commit Message

Bart Van Assche Aug. 30, 2017, 6:42 p.m. UTC 
Make sysfs writes fail for invalid numbers instead of storing
uninitialized data copied from the stack. This patch removes
all uninitialized_var() occurrences from the BFQ source code.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Paolo Valente <paolo.valente@linaro.org>
---
 block/bfq-iosched.c | 52 +++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 37 insertions(+), 15 deletions(-)

Comments

Paolo Valente Sept. 1, 2017, 5:14 p.m. UTC | #1 
> Il giorno 30 ago 2017, alle ore 20:42, Bart Van Assche <bart.vanassche@wdc.com> ha scritto:
> 
> Make sysfs writes fail for invalid numbers instead of storing
> uninitialized data copied from the stack. This patch removes
> all uninitialized_var() occurrences from the BFQ source code.
> 
> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
> Cc: Paolo Valente <paolo.valente@linaro.org>

Acked-by: Paolo Valente <paolo.valente@linaro.org>

> ---
> block/bfq-iosched.c | 52 +++++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 37 insertions(+), 15 deletions(-)
> 
> diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
> index 8c11c2e827a5..cf92f16eb5f2 100644
> --- a/block/bfq-iosched.c
> +++ b/block/bfq-iosched.c
> @@ -4802,13 +4802,15 @@ static ssize_t bfq_var_show(unsigned int var, char *page)
> 	return sprintf(page, "%u\n", var);
> }
> 
> -static void bfq_var_store(unsigned long *var, const char *page)
> +static int bfq_var_store(unsigned long *var, const char *page)
> {
> 	unsigned long new_val;
> 	int ret = kstrtoul(page, 10, &new_val);
> 
> -	if (ret == 0)
> -		*var = new_val;
> +	if (ret)
> +		return ret;
> +	*var = new_val;
> +	return 0;
> }
> 
> #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
> @@ -4849,8 +4851,12 @@ static ssize_t								\
> __FUNC(struct elevator_queue *e, const char *page, size_t count)	\
> {									\
> 	struct bfq_data *bfqd = e->elevator_data;			\
> -	unsigned long uninitialized_var(__data);			\
> -	bfq_var_store(&__data, (page));					\
> +	unsigned long __data;						\
> +	int ret;							\
> +									\
> +	ret = bfq_var_store(&__data, (page));				\
> +	if (ret)							\
> +		return ret;						\
> 	if (__data < (MIN))						\
> 		__data = (MIN);						\
> 	else if (__data > (MAX))					\
> @@ -4877,8 +4883,12 @@ STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
> static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\
> {									\
> 	struct bfq_data *bfqd = e->elevator_data;			\
> -	unsigned long uninitialized_var(__data);			\
> -	bfq_var_store(&__data, (page));					\
> +	unsigned long __data;						\
> +	int ret;							\
> +									\
> +	ret = bfq_var_store(&__data, (page));				\
> +	if (ret)							\
> +		return ret;						\
> 	if (__data < (MIN))						\
> 		__data = (MIN);						\
> 	else if (__data > (MAX))					\
> @@ -4894,9 +4904,12 @@ static ssize_t bfq_max_budget_store(struct elevator_queue *e,
> 				    const char *page, size_t count)
> {
> 	struct bfq_data *bfqd = e->elevator_data;
> -	unsigned long uninitialized_var(__data);
> +	unsigned long __data;
> +	int ret;
> 
> -	bfq_var_store(&__data, (page));
> +	ret = bfq_var_store(&__data, (page));
> +	if (ret)
> +		return ret;
> 
> 	if (__data == 0)
> 		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
> @@ -4919,9 +4932,12 @@ static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
> 				      const char *page, size_t count)
> {
> 	struct bfq_data *bfqd = e->elevator_data;
> -	unsigned long uninitialized_var(__data);
> +	unsigned long __data;
> +	int ret;
> 
> -	bfq_var_store(&__data, (page));
> +	ret = bfq_var_store(&__data, (page));
> +	if (ret)
> +		return ret;
> 
> 	if (__data < 1)
> 		__data = 1;
> @@ -4939,9 +4955,12 @@ static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
> 				     const char *page, size_t count)
> {
> 	struct bfq_data *bfqd = e->elevator_data;
> -	unsigned long uninitialized_var(__data);
> +	unsigned long __data;
> +	int ret;
> 
> -	bfq_var_store(&__data, (page));
> +	ret = bfq_var_store(&__data, (page));
> +	if (ret)
> +		return ret;
> 
> 	if (__data > 1)
> 		__data = 1;
> @@ -4958,9 +4977,12 @@ static ssize_t bfq_low_latency_store(struct elevator_queue *e,
> 				     const char *page, size_t count)
> {
> 	struct bfq_data *bfqd = e->elevator_data;
> -	unsigned long uninitialized_var(__data);
> +	unsigned long __data;
> +	int ret;
> 
> -	bfq_var_store(&__data, (page));
> +	ret = bfq_var_store(&__data, (page));
> +	if (ret)
> +		return ret;
> 
> 	if (__data > 1)
> 		__data = 1;
> -- 
> 2.14.1
>
Weiping Zhang Sept. 1, 2017, 5:37 p.m. UTC | #2 
2017-09-02 1:14 GMT+08:00 Paolo Valente <paolo.valente@linaro.org>:
>
>> Il giorno 30 ago 2017, alle ore 20:42, Bart Van Assche <bart.vanassche@wdc.com> ha scritto:
>>
>> Make sysfs writes fail for invalid numbers instead of storing
>> uninitialized data copied from the stack. This patch removes
>> all uninitialized_var() occurrences from the BFQ source code.
>>
>> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
>> Cc: Paolo Valente <paolo.valente@linaro.org>
>
> Acked-by: Paolo Valente <paolo.valente@linaro.org>
>

Hi Bart,

how about using simple_strtoul  which was used in cfq/mq-iosched.c
*var = simple_strtoul(p, &p, 10);

if invalid string came from sysfs, this function just return 0,
and there are validations after every calling bfq_var_store.

Thanks
Bart Van Assche Sept. 1, 2017, 5:41 p.m. UTC | #3 
On Sat, 2017-09-02 at 01:37 +0800, weiping zhang wrote:
> 2017-09-02 1:14 GMT+08:00 Paolo Valente <paolo.valente@linaro.org>:

> > Il giorno 30 ago 2017, alle ore 20:42, Bart Van Assche <bart.vanassche@wdc.com> ha scritto:

> > > 

> > > Make sysfs writes fail for invalid numbers instead of storing

> > > uninitialized data copied from the stack. This patch removes

> > > all uninitialized_var() occurrences from the BFQ source code.

> > > 

> > > Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>

> > > Cc: Paolo Valente <paolo.valente@linaro.org>

> > 

> > Acked-by: Paolo Valente <paolo.valente@linaro.org>

> 

> how about using simple_strtoul  which was used in cfq/mq-iosched.c

> *var = simple_strtoul(p, &p, 10);

> 

> if invalid string came from sysfs, this function just return 0,

> and there are validations after every calling bfq_var_store.


Hello Weiping,

Sorry but I do not like this proposal because:
* If invalid input is provided writing into a sysfs attribute should fail
  instead of ignoring the invalid input silently.
* simple_strtoul() is considered obsolete and must not be used in new code.
  From include/linux/kernel.h:

/* Obsolete, do not use.  Use kstrto<foo> instead */

extern unsigned long simple_strtoul(const char *,char **,unsigned int);
extern long simple_strtol(const char *,char **,unsigned int);
extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
extern long long simple_strtoll(const char *,char **,unsigned int);

Bart.
Weiping Zhang Sept. 1, 2017, 6:06 p.m. UTC | #4 
> Sorry but I do not like this proposal because:
> * If invalid input is provided writing into a sysfs attribute should fail
>   instead of ignoring the invalid input silently.
> * simple_strtoul() is considered obsolete and must not be used in new code.
>   From include/linux/kernel.h:
>
> /* Obsolete, do not use.  Use kstrto<foo> instead */
>
> extern unsigned long simple_strtoul(const char *,char **,unsigned int);
> extern long simple_strtol(const char *,char **,unsigned int);
> extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
> extern long long simple_strtoll(const char *,char **,unsigned int);
>

Hello Bart,

Agree with you, it seems more reasonable to give error message to user.

Thanks
diff mbox

Patch

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 8c11c2e827a5..cf92f16eb5f2 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -4802,13 +4802,15 @@  static ssize_t bfq_var_show(unsigned int var, char *page)
 	return sprintf(page, "%u\n", var);
 }
 
-static void bfq_var_store(unsigned long *var, const char *page)
+static int bfq_var_store(unsigned long *var, const char *page)
 {
 	unsigned long new_val;
 	int ret = kstrtoul(page, 10, &new_val);
 
-	if (ret == 0)
-		*var = new_val;
+	if (ret)
+		return ret;
+	*var = new_val;
+	return 0;
 }
 
 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
@@ -4849,8 +4851,12 @@  static ssize_t								\
 __FUNC(struct elevator_queue *e, const char *page, size_t count)	\
 {									\
 	struct bfq_data *bfqd = e->elevator_data;			\
-	unsigned long uninitialized_var(__data);			\
-	bfq_var_store(&__data, (page));					\
+	unsigned long __data;						\
+	int ret;							\
+									\
+	ret = bfq_var_store(&__data, (page));				\
+	if (ret)							\
+		return ret;						\
 	if (__data < (MIN))						\
 		__data = (MIN);						\
 	else if (__data > (MAX))					\
@@ -4877,8 +4883,12 @@  STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\
 {									\
 	struct bfq_data *bfqd = e->elevator_data;			\
-	unsigned long uninitialized_var(__data);			\
-	bfq_var_store(&__data, (page));					\
+	unsigned long __data;						\
+	int ret;							\
+									\
+	ret = bfq_var_store(&__data, (page));				\
+	if (ret)							\
+		return ret;						\
 	if (__data < (MIN))						\
 		__data = (MIN);						\
 	else if (__data > (MAX))					\
@@ -4894,9 +4904,12 @@  static ssize_t bfq_max_budget_store(struct elevator_queue *e,
 				    const char *page, size_t count)
 {
 	struct bfq_data *bfqd = e->elevator_data;
-	unsigned long uninitialized_var(__data);
+	unsigned long __data;
+	int ret;
 
-	bfq_var_store(&__data, (page));
+	ret = bfq_var_store(&__data, (page));
+	if (ret)
+		return ret;
 
 	if (__data == 0)
 		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
@@ -4919,9 +4932,12 @@  static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
 				      const char *page, size_t count)
 {
 	struct bfq_data *bfqd = e->elevator_data;
-	unsigned long uninitialized_var(__data);
+	unsigned long __data;
+	int ret;
 
-	bfq_var_store(&__data, (page));
+	ret = bfq_var_store(&__data, (page));
+	if (ret)
+		return ret;
 
 	if (__data < 1)
 		__data = 1;
@@ -4939,9 +4955,12 @@  static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
 				     const char *page, size_t count)
 {
 	struct bfq_data *bfqd = e->elevator_data;
-	unsigned long uninitialized_var(__data);
+	unsigned long __data;
+	int ret;
 
-	bfq_var_store(&__data, (page));
+	ret = bfq_var_store(&__data, (page));
+	if (ret)
+		return ret;
 
 	if (__data > 1)
 		__data = 1;
@@ -4958,9 +4977,12 @@  static ssize_t bfq_low_latency_store(struct elevator_queue *e,
 				     const char *page, size_t count)
 {
 	struct bfq_data *bfqd = e->elevator_data;
-	unsigned long uninitialized_var(__data);
+	unsigned long __data;
+	int ret;
 
-	bfq_var_store(&__data, (page));
+	ret = bfq_var_store(&__data, (page));
+	if (ret)
+		return ret;
 
 	if (__data > 1)
 		__data = 1;