lightnvm: fix up nonsensical configure overrun checking

Instead of checking a constant 0 actually check the space available. Even
better remember to allow for the header and also check the right amount of
space is needed.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 5 insertions, 6 deletions

diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
index 33224cb91c5b..782ac5d60a49 100644
--- a/drivers/lightnvm/core.c
+++ b/drivers/lightnvm/core.c
@@ -870,20 +870,19 @@ static int nvm_configure_by_str_event(const char *val,
 
 static int nvm_configure_get(char *buf, const struct kernel_param *kp)
 {
-        int sz = 0;
-        char *buf_start = buf;
+        int sz;
         struct nvm_dev *dev;
 
-        buf += sprintf(buf, "available devices:\n");
+        sz = sprintf(buf, "available devices:\n");
         down_write(&nvm_lock);
         list_for_each_entry(dev, &nvm_devices, devices) {
-                if (sz > 4095 - DISK_NAME_LEN)
+                if (sz > 4095 - DISK_NAME_LEN - 2)
                         break;
-                buf += sprintf(buf, " %32s\n", dev->name);
+                sz += sprintf(buf + sz, " %32s\n", dev->name);
         }
         up_write(&nvm_lock);
 
-        return buf - buf_start - 1;
+        return sz;
 }
 
 static const struct kernel_param_ops nvm_configure_by_str_event_param_ops = {