[PATCH net] platform/x86: intel_pmc_ipc: fix ACPI buffer memory leak

[yongxin.liu@windriver.com]

From: Yongxin Liu <yongxin.liu@windriver.com>

The intel_pmc_ipc() function uses ACPI_ALLOCATE_BUFFER to allocate memory
for the ACPI evaluation result but never frees it, causing a 192-byte
memory leak on each call.

This leak is triggered during network interface initialization when the
stmmac driver calls intel_mac_finish() -> intel_pmc_ipc().

  unreferenced object 0xffff96a848d6ea80 (size 192):
    comm "dhcpcd", pid 541, jiffies 4294684345
    hex dump (first 32 bytes):
      04 00 00 00 05 00 00 00 98 ea d6 48 a8 96 ff ff  ...........H....
      00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
    backtrace (crc b1564374):
      kmemleak_alloc+0x2d/0x40
      __kmalloc_noprof+0x2fa/0x730
      acpi_ut_initialize_buffer+0x83/0xc0
      acpi_evaluate_object+0x29a/0x2f0
      intel_pmc_ipc+0xfd/0x170
      intel_mac_finish+0x168/0x230
      stmmac_mac_finish+0x3d/0x50
      phylink_major_config+0x22b/0x5b0
      phylink_mac_initial_config.constprop.0+0xf1/0x1b0
      phylink_start+0x8e/0x210
      __stmmac_open+0x12c/0x2b0
      stmmac_open+0x23c/0x380
      __dev_open+0x11d/0x2c0
      __dev_change_flags+0x1d2/0x250
      netif_change_flags+0x2b/0x70
      dev_change_flags+0x40/0xb0

Add kfree() to properly release the allocated buffer.

Cc: stable@vger.kernel.org
Fixes: 7e2f7e25f6ff ("arch: x86: add IPC mailbox accessor function and add SoC register access")
Signed-off-by: Yongxin Liu <yongxin.liu@windriver.com>
---
 include/linux/platform_data/x86/intel_pmc_ipc.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/platform_data/x86/intel_pmc_ipc.h b/include/linux/platform_data/x86/intel_pmc_ipc.h
index 1d34435b7001..2fd5e684ce26 100644
--- a/include/linux/platform_data/x86/intel_pmc_ipc.h
+++ b/include/linux/platform_data/x86/intel_pmc_ipc.h
@@ -89,6 +89,7 @@ static inline int intel_pmc_ipc(struct pmc_ipc_cmd *ipc_cmd, struct pmc_ipc_rbuf
 		return -EINVAL;
 	}
 
+	kfree (obj);
 	return 0;
 #else
 	return -ENODEV;
-- 
2.46.2