regmap-irq: Use the new num_config_regs property in regmap_add_irq_chip_fwnode

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: regmap-irq: Use the new num_config_regs property in regmap_add_irq_chip_fwnode Commit faa87ce9196d ("regmap-irq: Introduce config registers for irq types") added the num_config_regs, then commit 9edd4f5aee84 ("regmap-irq: Deprecate type registers and virtual registers") suggested to replace num_type_reg with it. However, regmap_add_irq_chip_fwnode wasn't modified to use the new property. Later on, commit 255a03bb1bb3 ("ASoC: wcd9335: Convert irq chip to config regs") removed the old num_type_reg property from the WCD9335 driver's struct regmap_irq_chip, causing a null pointer dereference in regmap_irq_set_type when it tried to index d->type_buf as it was never allocated in regmap_add_irq_chip_fwnode: [ 39.199374] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 [ 39.200006] Call trace: [ 39.200014] regmap_irq_set_type+0x84/0x1c0 [ 39.200026] __irq_set_trigger+0x60/0x1c0 [ 39.200040] __setup_irq+0x2f4/0x78c [ 39.200051] request_threaded_irq+0xe8/0x1a0 Use num_config_regs in regmap_add_irq_chip_fwnode instead of num_type_reg, and fall back to it if num_config_regs isn't defined to maintain backward compatibility.

References

• https://git.kernel.org/stable/c/57bb34330c0fc70bb4ab96399a3c1b80e73e9d49
• https://git.kernel.org/stable/c/961db32e52f4d34a9a95939a30393fd190397f84
• https://git.kernel.org/stable/c/84498d1fb35de6ab71bdfdb6270a464fb4a0951b