In the Linux kernel, the following vulnerability has been resolved:
ibmvnic: don't release napi in _ibmvnicopen()
If _ibmvnicopen() encounters an error such as when setting link state, it calls releaseresources() which frees the napi structures needlessly. Instead, have _ibmvnic_open() only clean up the work it did so far (i.e. disable napi and irqs) and leave the rest to the callers.
If caller of _ibmvnicopen() is ibmvnicopen(), it should release the resources immediately. If the caller is doreset() or dohardreset(), they will release the resources on the next reset.
This fixes following crash that occurred when running the drmgr command several times to add/remove a vnic interface:
[102056] ibmvnic 30000003 env3: Disabling rx_scrq[6] irq
[102056] ibmvnic 30000003 env3: Disabling rx_scrq[7] irq
[102056] ibmvnic 30000003 env3: Replenished 8 pools
Kernel attempted to read user page (10) - exploit attempt? (uid: 0)
BUG: Kernel NULL pointer dereference on read at 0x00000010
Faulting instruction address: 0xc000000000a3c840
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
...
CPU: 9 PID: 102056 Comm: kworker/9:2 Kdump: loaded Not tainted 5.16.0-rc5-autotest-g6441998e2e37 #1
Workqueue: events_long __ibmvnic_reset [ibmvnic]
NIP: c000000000a3c840 LR: c0080000029b5378 CTR: c000000000a3c820
REGS: c0000000548e37e0 TRAP: 0300 Not tainted (5.16.0-rc5-autotest-g6441998e2e37)
MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 28248484 XER: 00000004
CFAR: c0080000029bdd24 DAR: 0000000000000010 DSISR: 40000000 IRQMASK: 0
GPR00: c0080000029b55d0 c0000000548e3a80 c0000000028f0200 0000000000000000
...
NIP [c000000000a3c840] napi_enable+0x20/0xc0
LR [c0080000029b5378] __ibmvnic_open+0xf0/0x430 [ibmvnic]
Call Trace:
[c0000000548e3a80] [0000000000000006] 0x6 (unreliable)
[c0000000548e3ab0] [c0080000029b55d0] __ibmvnic_open+0x348/0x430 [ibmvnic]
[c0000000548e3b40] [c0080000029bcc28] __ibmvnic_reset+0x500/0xdf0 [ibmvnic]
[c0000000548e3c60] [c000000000176228] process_one_work+0x288/0x570
[c0000000548e3d00] [c000000000176588] worker_thread+0x78/0x660
[c0000000548e3da0] [c0000000001822f0] kthread+0x1c0/0x1d0
[c0000000548e3e10] [c00000000000cf64] ret_from_kernel_thread+0x5c/0x64
Instruction dump:
7d2948f8 792307e0 4e800020 60000000 3c4c01eb 384239e0 f821ffd1 39430010
38a0fff6 e92d1100 f9210028 39200000 <e9030010> f9010020 60420000 e9210020
---[ end trace 5f8033b08fd27706 ]---