Input: make modalias code respect allowed buffer size

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 71 insertions, 39 deletions

diff --git a/drivers/input/input.c b/drivers/input/input.c
index db52ba0a316f..a935abeffffc 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -571,15 +571,16 @@ INPUT_DEV_STRING_ATTR_SHOW(name);
 INPUT_DEV_STRING_ATTR_SHOW(phys);
 INPUT_DEV_STRING_ATTR_SHOW(uniq);
 
-static int print_modalias_bits(char *buf, int size, char prefix, unsigned long *arr,
-                               unsigned int min, unsigned int max)
+static int input_print_modalias_bits(char *buf, int size,
+                                     char name, unsigned long *bm,
+                                     unsigned int min_bit, unsigned int max_bit)
 {
-        int len, i;
+        int len = 0, i;
 
-        len = snprintf(buf, size, "%c", prefix);
-        for (i = min; i < max; i++)
-                if (arr[LONG(i)] & BIT(i))
-                        len += snprintf(buf + len, size - len, "%X,", i);
+        len += snprintf(buf, max(size, 0), "%c", name);
+        for (i = min_bit; i < max_bit; i++)
+                if (bm[LONG(i)] & BIT(i))
+                        len += snprintf(buf + len, max(size - len, 0), "%X,", i);
         return len;
 }
 
@@ -588,33 +589,32 @@ static int input_print_modalias(char *buf, int size, struct input_dev *id,
 {
         int len;
 
-        len = snprintf(buf, size, "input:b%04Xv%04Xp%04Xe%04X-",
-                       id->id.bustype,
-                       id->id.vendor,
-                       id->id.product,
-                       id->id.version);
-
-        len += print_modalias_bits(buf + len, size - len, 'e', id->evbit,
-                                   0, EV_MAX);
-        len += print_modalias_bits(buf + len, size - len, 'k', id->keybit,
-                                   KEY_MIN_INTERESTING, KEY_MAX);
-        len += print_modalias_bits(buf + len, size - len, 'r', id->relbit,
-                                   0, REL_MAX);
-        len += print_modalias_bits(buf + len, size - len, 'a', id->absbit,
-                                   0, ABS_MAX);
-        len += print_modalias_bits(buf + len, size - len, 'm', id->mscbit,
-                                   0, MSC_MAX);
-        len += print_modalias_bits(buf + len, size - len, 'l', id->ledbit,
-                                   0, LED_MAX);
-        len += print_modalias_bits(buf + len, size - len, 's', id->sndbit,
-                                   0, SND_MAX);
-        len += print_modalias_bits(buf + len, size - len, 'f', id->ffbit,
-                                   0, FF_MAX);
-        len += print_modalias_bits(buf + len, size - len, 'w', id->swbit,
-                                   0, SW_MAX);
+        len = snprintf(buf, max(size, 0),
+                       "input:b%04Xv%04Xp%04Xe%04X-",
+                       id->id.bustype, id->id.vendor,
+                       id->id.product, id->id.version);
+
+        len += input_print_modalias_bits(buf + len, size - len,
+                                'e', id->evbit, 0, EV_MAX);
+        len += input_print_modalias_bits(buf + len, size - len,
+                                'k', id->keybit, KEY_MIN_INTERESTING, KEY_MAX);
+        len += input_print_modalias_bits(buf + len, size - len,
+                                'r', id->relbit, 0, REL_MAX);
+        len += input_print_modalias_bits(buf + len, size - len,
+                                'a', id->absbit, 0, ABS_MAX);
+        len += input_print_modalias_bits(buf + len, size - len,
+                                'm', id->mscbit, 0, MSC_MAX);
+        len += input_print_modalias_bits(buf + len, size - len,
+                                'l', id->ledbit, 0, LED_MAX);
+        len += input_print_modalias_bits(buf + len, size - len,
+                                's', id->sndbit, 0, SND_MAX);
+        len += input_print_modalias_bits(buf + len, size - len,
+                                'f', id->ffbit, 0, FF_MAX);
+        len += input_print_modalias_bits(buf + len, size - len,
+                                'w', id->swbit, 0, SW_MAX);
 
         if (add_cr)
-                len += snprintf(buf + len, size - len, "\n");
+                len += snprintf(buf + len, max(size - len, 0), "\n");
 
         return len;
 }
@@ -739,8 +739,8 @@ static void input_dev_release(struct class_device *class_dev)
  * device bitfields.
  */
 static int input_add_uevent_bm_var(char **envp, int num_envp, int *cur_index,
-                                    char *buffer, int buffer_size, int *cur_len,
-                                    const char *name, unsigned long *bitmap, int max)
+                                   char *buffer, int buffer_size, int *cur_len,
+                                   const char *name, unsigned long *bitmap, int max)
 {
         if (*cur_index >= num_envp - 1)
                 return -ENOMEM;
@@ -748,7 +748,7 @@ static int input_add_uevent_bm_var(char **envp, int num_envp, int *cur_index,
         envp[*cur_index] = buffer + *cur_len;
 
         *cur_len += snprintf(buffer + *cur_len, max(buffer_size - *cur_len, 0), name);
-        if (*cur_len > buffer_size)
+        if (*cur_len >= buffer_size)
                 return -ENOMEM;
 
         *cur_len += input_print_bitmap(buffer + *cur_len,
@@ -761,9 +761,33 @@ static int input_add_uevent_bm_var(char **envp, int num_envp, int *cur_index,
         return 0;
 }
 
+static int input_add_uevent_modalias_var(char **envp, int num_envp, int *cur_index,
+                                         char *buffer, int buffer_size, int *cur_len,
+                                         struct input_dev *dev)
+{
+        if (*cur_index >= num_envp - 1)
+                return -ENOMEM;
+
+        envp[*cur_index] = buffer + *cur_len;
+
+        *cur_len += snprintf(buffer + *cur_len, max(buffer_size - *cur_len, 0),
+                             "MODALIAS=");
+        if (*cur_len >= buffer_size)
+                return -ENOMEM;
+
+        *cur_len += input_print_modalias(buffer + *cur_len,
+                                         max(buffer_size - *cur_len, 0),
+                                         dev, 0) + 1;
+        if (*cur_len > buffer_size)
+                return -ENOMEM;
+
+        (*cur_index)++;
+        return 0;
+}
+
 #define INPUT_ADD_HOTPLUG_VAR(fmt, val...)                              \
         do {                                                            \
-                int err = add_uevent_var(envp, num_envp, &i,    \
+                int err = add_uevent_var(envp, num_envp, &i,            \
                                         buffer, buffer_size, &len,      \
                                         fmt, val);                      \
                 if (err)                                                \
@@ -779,6 +803,16 @@ static int input_add_uevent_bm_var(char **envp, int num_envp, int *cur_index,
                         return err;                                     \
         } while (0)
 
+#define INPUT_ADD_HOTPLUG_MODALIAS_VAR(dev)                             \
+        do {                                                            \
+                int err = input_add_uevent_modalias_var(envp,           \
+                                        num_envp, &i,                   \
+                                        buffer, buffer_size, &len,      \
+                                        dev);                           \
+                if (err)                                                \
+                        return err;                                     \
+        } while (0)
+
 static int input_dev_uevent(struct class_device *cdev, char **envp,
                             int num_envp, char *buffer, int buffer_size)
 {
@@ -814,9 +848,7 @@ static int input_dev_uevent(struct class_device *cdev, char **envp,
         if (test_bit(EV_SW, dev->evbit))
                 INPUT_ADD_HOTPLUG_BM_VAR("SW=", dev->swbit, SW_MAX);
 
-        envp[i++] = buffer + len;
-        len += snprintf(buffer + len, buffer_size - len, "MODALIAS=");
-        len += input_print_modalias(buffer + len, buffer_size - len, dev, 0) + 1;
+        INPUT_ADD_HOTPLUG_MODALIAS_VAR(dev);
 
         envp[i] = NULL;
         return 0;