bfq: Check kstrtoul() return value

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.

Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 856f4199a4700cc2938ba36d4ce23717abb8f14a..0f286cd5da95d262539fdbc67cf1ea112b54f826 100644 (file)
--- 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;