CVE-2022-50545

Summary

In the Linux kernel, the following vulnerability has been resolved:

r6040: Fix kmemleak in probe and remove

There is a memory leaks reported by kmemleak:

unreferenced object 0xffff888116111000 (size 2048): comm "modprobe", pid 817, jiffies 4294759745 (age 76.502s) hex dump (first 32 bytes): 00 c4 0a 04 81 88 ff ff 08 10 11 16 81 88 ff ff ……………. 08 10 11 16 81 88 ff ff 00 00 00 00 00 00 00 00 ……………. backtrace: [<ffffffff815bcd82>] kmalloc_trace+0x22/0x60 [<ffffffff827e20ee>] phy_device_create+0x4e/0x90 [<ffffffff827e6072>] get_phy_device+0xd2/0x220 [<ffffffff827e7844>] mdiobus_scan+0xa4/0x2e0 [<ffffffff827e8be2>] __mdiobus_register+0x482/0x8b0 [<ffffffffa01f5d24>] r6040_init_one+0x714/0xd2c [r6040] …

The problem occurs in probe process as follows: r6040_init_one: mdiobus_register mdiobus_scan <- alloc and register phy_device, the reference count of phy_device is 3 r6040_mii_probe phy_connect <- connect to the first phy_device, so the reference count of the first phy_device is 4, others are 3 register_netdev <- fault inject succeeded, goto error handling path

// error handling path
err_out_mdio_unregister:
  mdiobus_unregister(lp->mii_bus);
err_out_mdio:
  mdiobus_free(lp->mii_bus);    <- the reference count of the first
                                   phy_device is 1, it is not released
                                   and other phy_devices are released

// similarly, the remove process also has the same problem

The root cause is traced to the phy_device is not disconnected when removes one r6040 device in r6040_remove_one() or on error handling path after r6040_mii probed successfully. In r6040_mii_probe(), a net ethernet device is connected to the first PHY device of mii_bus, in order to notify the connected driver when the link status changes, which is the default behavior of the PHY infrastructure to handle everything. Therefore the phy_device should be disconnected when removes one r6040 device or on error handling path.

Fix it by adding phy_disconnect() when removes one r6040 device or on error handling path after r6040_mii probed successfully.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/a04707f4596952049da05756c27398c34d9a1d36
• https://git.kernel.org/stable/c/b4448816e6a565e08236a6009c6bf48c6836cdfd
• https://git.kernel.org/stable/c/2ce242e1b9ad31c1f68496b3548e407a8cb2c07d
• https://git.kernel.org/stable/c/b0a61359026b57a287a48fbb4ba1d097023eca3e
• https://git.kernel.org/stable/c/3d5f83a62e8235d235534b3dc6f197d8a822c269
• https://git.kernel.org/stable/c/9b5b50329e2e966831a7237dd6949e7b5362a49a
• https://git.kernel.org/stable/c/ad2c8f25457ca9a81e7e958148cbc26600ce3071
• https://git.kernel.org/stable/c/5944c25c67de54e0aa53623e1e1af3bf8b16ed44
• https://git.kernel.org/stable/c/7e43039a49c2da45edc1d9d7c9ede4003ab45a5f

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