powercap: intel_rapl: add NULL pointer check to rapl_mmio_cpu_online() ...
RAPL MMIO support depends on the RAPL common driver. During CPU
initialization rapl_mmio_cpu_online() is called via CPU hotplug
to initialize the MMIO RAPL for the new CPU, but if that CPU is
not present in the common RAPL driver's support list, rapl_defaults
is NULL and the kernel crashes on an attempt to dereference it:
[ 4.188566] BUG: kernel NULL pointer dereference, address: 0000000000000020
...snip...
[ 4.189555] RIP: 0010:rapl_add_package+0x223/0x574
[ 4.189555] Code: b5 a0 31 c0 49 8b 4d 78 48 01 d9 48 8b 0c c1 49 89 4c c6 10 48 ff c0 48 83 f8 05 75 e7 49 83 ff 03 75 15 48 8b 05 09 bc 18 01 <8b> 70 20 41 89 b6 0c 05 00 00 85 f6 75 1a 49 81 c6 18 9
[ 4.189555] RSP: 0000:ffffb3adc00b3d90 EFLAGS: 00010246
[ 4.189555] RAX: 0000000000000000 RBX: 0000000000000098 RCX: 0000000000000000
[ 4.267161] usb 1-1: New USB device found, idVendor=2109, idProduct=2812, bcdDevice= b.e0
[ 4.189555] RDX: 0000000000001000 RSI: 0000000000000000 RDI: ffff9340caafd000
[ 4.189555] RBP: ffffb3adc00b3df8 R08: ffffffffa0246e28 R09: ffff9340caafc000
[ 4.189555] R10: 000000000000024a R11: ffffffff9ff1f6f2 R12: 00000000ffffffed
[ 4.189555] R13: ffff9340caa94800 R14: ffff9340caafc518 R15: 0000000000000003
[ 4.189555] FS: 0000000000000000(0000) GS:ffff9340ce200000(0000) knlGS:0000000000000000
[ 4.189555] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 4.189555] CR2: 0000000000000020 CR3: 0000000302c14001 CR4: 00000000003606f0
[ 4.189555] Call Trace:
[ 4.189555] ? __switch_to_asm+0x40/0x70
[ 4.189555] rapl_mmio_cpu_online+0x47/0x64
[ 4.189555] ? rapl_mmio_write_raw+0x33/0x33
[ 4.281059] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 4.189555] cpuhp_invoke_callback+0x29f/0x66f
[ 4.189555] ? __schedule+0x46d/0x6a0
[ 4.189555] cpuhp_thread_fun+0xb9/0x11c
[ 4.189555] smpboot_thread_fn+0x17d/0x22f
[ 4.297006] usb 1-1: Product: USB2.0 Hub
[ 4.189555] ? cpu_report_death+0x43/0x43
[ 4.189555] kthread+0x137/0x13f
[ 4.189555] ? cpu_report_death+0x43/0x43
[ 4.189555] ? kthread_blkcg+0x2e/0x2e
[ 4.312951] usb 1-1: Manufacturer: VIA Labs, Inc.
[ 4.189555] ret_from_fork+0x1f/0x40
[ 4.189555] Modules linked in:
[ 4.189555] CR2: 0000000000000020
[ 4.189555] ---[ end trace 01bb812aabc791f4 ]---
To avoid that problem, check rapl_defaults NULL upfront and return an
error code if it is NULL. [Note that it does not make sense to even
try to allocate memory in that case, because it is not going to be
used anyway.]
Fixes: 555c45fe0d
3aa3c5882e