CVE-2021-47100

In the Linux kernel, the following vulnerability has been resolved: ipmi:
Fix UAF when uninstall ipmi_si and ipmi_msghandler module Hi, When testing
install and uninstall of ipmi_si.ko and ipmi_msghandler.ko, the system
crashed. The log as follows: [ 141.087026] BUG: unable to handle kernel
paging request at ffffffffc09b3a5a [ 141.087241] PGD 8fe4c0d067 P4D
8fe4c0d067 PUD 8fe4c0f067 PMD 103ad89067 PTE 0 [ 141.087464] Oops: 0010
[#1] SMP NOPTI [ 141.087580] CPU: 67 PID: 668 Comm: kworker/67:1 Kdump:
loaded Not tainted 4.18.0.x86_64 #47 [ 141.088009] Workqueue: events
0xffffffffc09b3a40 [ 141.088009] RIP: 0010:0xffffffffc09b3a5a [ 141.088009]
Code: Bad RIP value. [ 141.088009] RSP: 0018:ffffb9094e2c3e88 EFLAGS:
00010246 [ 141.088009] RAX: 0000000000000000 RBX: ffff9abfdb1f04a0 RCX:
0000000000000000 [ 141.088009] RDX: 0000000000000000 RSI: 0000000000000246
RDI: 0000000000000246 [ 141.088009] RBP: 0000000000000000 R08:
ffff9abfffee3cb8 R09: 00000000000002e1 [ 141.088009] R10: ffffb9094cb73d90
R11: 00000000000f4240 R12: ffff9abfffee8700 [ 141.088009] R13:
0000000000000000 R14: ffff9abfdb1f04a0 R15: ffff9abfdb1f04a8 [ 141.088009]
FS: 0000000000000000(0000) GS:ffff9abfffec0000(0000) knlGS:0000000000000000
[ 141.088009] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [
141.088009] CR2: ffffffffc09b3a30 CR3: 0000008fe4c0a001 CR4:
00000000007606e0 [ 141.088009] DR0: 0000000000000000 DR1: 0000000000000000
DR2: 0000000000000000 [ 141.088009] DR3: 0000000000000000 DR6:
00000000fffe0ff0 DR7: 0000000000000400 [ 141.088009] PKRU: 55555554 [
141.088009] Call Trace: [ 141.088009] ? process_one_work+0x195/0x390 [
141.088009] ? worker_thread+0x30/0x390 [ 141.088009] ?
process_one_work+0x390/0x390 [ 141.088009] ? kthread+0x10d/0x130 [
141.088009] ? kthread_flush_work_fn+0x10/0x10 [ 141.088009] ?
ret_from_fork+0x35/0x40] BUG: unable to handle kernel paging request at
ffffffffc0b28a5a [ 200.223240] PGD 97fe00d067 P4D 97fe00d067 PUD 97fe00f067
PMD a580cbf067 PTE 0 [ 200.223464] Oops: 0010 [#1] SMP NOPTI [ 200.223579]
CPU: 63 PID: 664 Comm: kworker/63:1 Kdump: loaded Not tainted 4.18.0.x86_64
#46 [ 200.224008] Workqueue: events 0xffffffffc0b28a40 [ 200.224008] RIP:
0010:0xffffffffc0b28a5a [ 200.224008] Code: Bad RIP value. [ 200.224008]
RSP: 0018:ffffbf3c8e2a3e88 EFLAGS: 00010246 [ 200.224008] RAX:
0000000000000000 RBX: ffffa0799ad6bca0 RCX: 0000000000000000 [ 200.224008]
RDX: 0000000000000000 RSI: 0000000000000246 RDI: 0000000000000246 [
200.224008] RBP: 0000000000000000 R08: ffff9fe43fde3cb8 R09:
00000000000000d5 [ 200.224008] R10: ffffbf3c8cb53d90 R11: 00000000000f4240
R12: ffff9fe43fde8700 [ 200.224008] R13: 0000000000000000 R14:
ffffa0799ad6bca0 R15: ffffa0799ad6bca8 [ 200.224008] FS:
0000000000000000(0000) GS:ffff9fe43fdc0000(0000) knlGS:0000000000000000 [
200.224008] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 200.224008]
CR2: ffffffffc0b28a30 CR3: 00000097fe00a002 CR4: 00000000007606e0 [
200.224008] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000 [ 200.224008] DR3: 0000000000000000 DR6: 00000000fffe0ff0
DR7: 0000000000000400 [ 200.224008] PKRU: 55555554 [ 200.224008] Call
Trace: [ 200.224008] ? process_one_work+0x195/0x390 [ 200.224008] ?
worker_thread+0x30/0x390 [ 200.224008] ? process_one_work+0x390/0x390 [
200.224008] ? kthread+0x10d/0x130 [ 200.224008] ?
kthread_flush_work_fn+0x10/0x10 [ 200.224008] ? ret_from_fork+0x35/0x40 [
200.224008] kernel fault(0x1) notification starting on CPU 63 [ 200.224008]
kernel fault(0x1) notification finished on CPU 63 [ 200.224008] CR2:
ffffffffc0b28a5a [ 200.224008] —[ end trace c82a412d93f57412 ]— The
reason is as follows: T1: rmmod ipmi_si. ->ipmi_unregister_smi() ->
ipmi_bmc_unregister() -> __ipmi_bmc_unregister() ->
kref_put(&bmc->usecount, cleanup_bmc_device); ->
schedule_work(&bmc->remove_work); T2: rmmod ipmi_msghandl —truncated—

Notes