regmap: fix potential memory leak of regmap_bus

When __regmap_init() is called from __regmap_init_i2c() and
__regmap_init_spi() (and their devm versions), the bus argument
obtained from regmap_get_i2c_bus() and regmap_get_spi_bus(), may be
allocated using kmemdup() to support quirks. In those cases, the
bus->free_on_exit field is set to true.

However, inside __regmap_init(), buf is not freed on any error path.
This could lead to a memory leak of regmap_bus when __regmap_init()
fails. Fix that by freeing bus on error path when free_on_exit is set.

Fixes: ea030ca ("regmap-i2c: Set regmap max raw r/w from quirks")
Signed-off-by: Abdun Nihaal <abdun.nihaal@gmail.com>
Link: https://patch.msgid.link/20250626172823.18725-1-abdun.nihaal@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: nifey

drivers/base/regmap/regmap.c

@@ -1173,6 +1173,8 @@ struct regmap *__regmap_init(struct device *dev,
 err_map:
 	kfree(map);
 err:
+	if (bus && bus->free_on_exit)
+		kfree(bus);
 	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(__regmap_init);