driver core: Fix size calculation of symlink name for devlink_(add|remove)_symlinks()

devlink_(add|remove)_symlinks() kzalloc() memory to save symlink name
for both supplier and consumer, but do not explicitly take into account
consumer's prefix "consumer:", so cause disadvantages listed below:
1) it seems wrong for the algorithm to calculate memory size
2) readers maybe need to count characters one by one of both prefix
   strings to confirm calculated memory size
3) it is relatively easy to introduce new bug if either prefix string
   is modified in future
solved by taking into account consumer's prefix as well.

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20240712-devlink_fix-v3-1-fa1c5172ffc7@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 730cae66607c02530d456b61344d431dc313c031..3e82eaba493265c0baf1e05f41948ea4c63fa392 100644 (file)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -572,7 +572,11 @@ static int devlink_add_symlinks(struct device *dev)
        len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
                  strlen(dev_bus_name(con)) + strlen(dev_name(con)));
        len += strlen(":");
-       len += strlen("supplier:") + 1;
+       /*
+        * we kzalloc() memory for symlink name of both supplier and
+        * consumer, so explicitly take into account both prefix.
+        */
+       len += max(strlen("supplier:"), strlen("consumer:")) + 1;
        buf = kzalloc(len, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;
@@ -623,7 +627,7 @@ static void devlink_remove_symlinks(struct device *dev)
        len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
                  strlen(dev_bus_name(con)) + strlen(dev_name(con)));
        len += strlen(":");
-       len += strlen("supplier:") + 1;
+       len += max(strlen("supplier:"), strlen("consumer:")) + 1;
        buf = kzalloc(len, GFP_KERNEL);
        if (!buf) {
                WARN(1, "Unable to properly free device link symlinks!\n");