CVE-2022-49021

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

net: phy: fix null-ptr-deref while probe() failed

I got a null-ptr-deref report as following when doing fault injection test:

BUG: kernel NULL pointer dereference, address: 0000000000000058 Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 1 PID: 253 Comm: 507-spi-dm9051 Tainted: G B N 6.1.0-rc3+ Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: 0010:klist_put+0x2d/0xd0 Call Trace: klist_remove+0xf1/0x1c0 device_release_driver_internal+0x23e/0x2d0 bus_remove_device+0x1bd/0x240 device_del+0x357/0x770 phy_device_remove+0x11/0x30 mdiobus_unregister+0xa5/0x140 release_nodes+0x6a/0xa0 devres_release_all+0xf8/0x150 device_unbind_cleanup+0x19/0xd0

//probe path: phy_device_register() device_add()

phy_connect phy_attach_direct() //set device driver probe() //its failed, driver is not bound device_bind_driver() // probe failed, its not called

//remove path: phy_device_remove() device_del() device_release_driver_internal() __device_release_driver() //dev->drv is not NULL klist_remove() <- knode_driver is not added yet, cause null-ptr-deref

In phy_attach_direct(), after setting the dev->driver, probe() fails, device_bind_driver() is not called, so the knode_driver->n_klist is not set, then it causes null-ptr-deref in __device_release_driver() while deleting device. Fix this by setting dev->driver to NULL in the error path in phy_attach_direct().

Weakness

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/0744c7be4de564db03e24527b2e096b7e0e20972
• https://git.kernel.org/stable/c/369eb2c9f1f72adbe91e0ea8efb130f0a2ba11a6
• https://git.kernel.org/stable/c/3e21f85d87c836462bb52ef2078ea561260935c1
• https://git.kernel.org/stable/c/51d7f6b20fae8bae64ad1136f1e30d1fd5ba78f7
• https://git.kernel.org/stable/c/7730904f50c7187dd16c76949efb56b5fb55cd57
• https://git.kernel.org/stable/c/8aaafe0f71314f46a066382a047ba8bb3840d273
• https://git.kernel.org/stable/c/eaa5722549ac2604ffa56c2e946acc83226f130c
• https://git.kernel.org/stable/c/fe6bc99c27c21348f548966118867ed26a9a372c