CVE-2024-40906 net/mlx5: Always stop health timer during driver removal
In the Linux kernel, the following vulnerability has been resolved:

net/mlx5: Always stop health timer during driver removal

Currently, if teardown_hca fails to execute during driver removal, mlx5
does not stop the health timer. Afterwards, mlx5 continue with driver
teardown. This may lead to a UAF bug, which results in page fault
Oops[1], since the health timer invokes after resources were freed.

Hence, stop the health monitor even if teardown_hca fails.

[1]
mlx5_core 0000:18:00.0: E-Switch: Unload vfs: mode(LEGACY), nvfs(0), necvfs(0), active vports(0)
mlx5_core 0000:18:00.0: E-Switch: Disable: mode(LEGACY), nvfs(0), necvfs(0), active vports(0)
mlx5_core 0000:18:00.0: E-Switch: Disable: mode(LEGACY), nvfs(0), necvfs(0), active vports(0)
mlx5_core 0000:18:00.0: E-Switch: cleanup
mlx5_core 0000:18:00.0: wait_func:1155:(pid 1967079): TEARDOWN_HCA(0x103) timeout. Will cause a leak of a command resource
mlx5_core 0000:18:00.0: mlx5_function_close:1288:(pid 1967079): tear_down_hca failed, skip cleanup
BUG: unable to handle page fault for address: ffffa26487064230
PGD 100c00067 P4D 100c00067 PUD 100e5a067 PMD 105ed7067 PTE 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 PID: 0 Comm: swapper/0 Tainted: G           OE     -------  ---  6.7.0-68.fc38.x86_64 #1
Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0013.121520200651 12/15/2020
RIP: 0010:ioread32be+0x34/0x60
RSP: 0018:ffffa26480003e58 EFLAGS: 00010292
RAX: ffffa26487064200 RBX: ffff9042d08161a0 RCX: ffff904c108222c0
RDX: 000000010bbf1b80 RSI: ffffffffc055ddb0 RDI: ffffa26487064230
RBP: ffff9042d08161a0 R08: 0000000000000022 R09: ffff904c108222e8
R10: 0000000000000004 R11: 0000000000000441 R12: ffffffffc055ddb0
R13: ffffa26487064200 R14: ffffa26480003f00 R15: ffff904c108222c0
FS:  0000000000000000(0000) GS:ffff904c10800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffa26487064230 CR3: 00000002c4420006 CR4: 00000000007706f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <IRQ>
 ? __die+0x23/0x70
 ? page_fault_oops+0x171/0x4e0
 ? exc_page_fault+0x175/0x180
 ? asm_exc_page_fault+0x26/0x30
 ? __pfx_poll_health+0x10/0x10 [mlx5_core]
 ? __pfx_poll_health+0x10/0x10 [mlx5_core]
 ? ioread32be+0x34/0x60
 mlx5_health_check_fatal_sensors+0x20/0x100 [mlx5_core]
 ? __pfx_poll_health+0x10/0x10 [mlx5_core]
 poll_health+0x42/0x230 [mlx5_core]
 ? __next_timer_interrupt+0xbc/0x110
 ? __pfx_poll_health+0x10/0x10 [mlx5_core]
 call_timer_fn+0x21/0x130
 ? __pfx_poll_health+0x10/0x10 [mlx5_core]
 __run_timers+0x222/0x2c0
 run_timer_softirq+0x1d/0x40
 __do_softirq+0xc9/0x2c8
 __irq_exit_rcu+0xa6/0xc0
 sysvec_apic_timer_interrupt+0x72/0x90
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:cpuidle_enter_state+0xcc/0x440
 ? cpuidle_enter_state+0xbd/0x440
 cpuidle_enter+0x2d/0x40
 do_idle+0x20d/0x270
 cpu_startup_entry+0x2a/0x30
 rest_init+0xd0/0xd0
 arch_call_rest_init+0xe/0x30
 start_kernel+0x709/0xa90
 x86_64_start_reservations+0x18/0x30
 x86_64_start_kernel+0x96/0xa0
 secondary_startup_64_no_verify+0x18f/0x19b
---[ end trace 0000000000000000 ]---
CVSS v3.1 score: 7.8