On 2023/11/22 20:02, Leon Romanovsky wrote:
On Tue, Nov 21, 2023 at 03:52:51AM -0800, Shifeng Li wrote:
Fix a cmd->ent use after free due to a race on command entry.
Such race occurs when one of the commands releases its last refcount and
frees its index and entry while another process running command flush
flow takes refcount to this command entry. The process which handles
commands flush may see this command as needed to be flushed if the other
process allocated a ent->idx but didn't set ent to cmd->ent_arr in
cmd_work_handler(). Fix it by moving the assignment of cmd->ent_arr into
the spin lock.
[70013.081955] BUG: KASAN: use-after-free in mlx5_cmd_trigger_completions+0x1e2/0x4c0 [mlx5_core]
[70013.081967] Write of size 4 at addr ffff88880b1510b4 by task kworker/26:1/1433361
[70013.081968]
[70013.081989] CPU: 26 PID: 1433361 Comm: kworker/26:1 Kdump: loaded Tainted: G OE 4.19.90-25.17.v2101.osc.sfc.6.10.0.0030.ky10.x86_64+debug #1
[70013.082001] Hardware name: SANGFOR 65N32-US/ASERVER-G-2605, BIOS SSSS5203 08/19/2020
[70013.082028] Workqueue: events aer_isr
[70013.082053] Call Trace:
[70013.082067] dump_stack+0x8b/0xbb
[70013.082086] print_address_description+0x6a/0x270
[70013.082102] kasan_report+0x179/0x2c0
[70013.082133] ? mlx5_cmd_trigger_completions+0x1e2/0x4c0 [mlx5_core]
[70013.082173] mlx5_cmd_trigger_completions+0x1e2/0x4c0 [mlx5_core]
[70013.082213] ? mlx5_cmd_use_polling+0x20/0x20 [mlx5_core]
[70013.082223] ? kmem_cache_free+0x1ad/0x1e0
[70013.082267] mlx5_cmd_flush+0x80/0x180 [mlx5_core]
[70013.082304] mlx5_enter_error_state+0x106/0x1d0 [mlx5_core]
[70013.082338] mlx5_try_fast_unload+0x2ea/0x4d0 [mlx5_core]
[70013.082377] remove_one+0x200/0x2b0 [mlx5_core]
[70013.082390] ? __pm_runtime_resume+0x58/0x70
[70013.082409] pci_device_remove+0xf3/0x280
[70013.082426] ? pcibios_free_irq+0x10/0x10
[70013.082439] device_release_driver_internal+0x1c3/0x470
[70013.082453] pci_stop_bus_device+0x109/0x160
[70013.082468] pci_stop_and_remove_bus_device+0xe/0x20
[70013.082485] pcie_do_fatal_recovery+0x167/0x550
[70013.082493] aer_isr+0x7d2/0x960
[70013.082510] ? aer_get_device_error_info+0x420/0x420
[70013.082526] ? __schedule+0x821/0x2040
[70013.082536] ? strscpy+0x85/0x180
[70013.082543] process_one_work+0x65f/0x12d0
[70013.082556] worker_thread+0x87/0xb50
[70013.082563] ? __kthread_parkme+0x82/0xf0
[70013.082569] ? process_one_work+0x12d0/0x12d0
[70013.082571] kthread+0x2e9/0x3a0
[70013.082579] ? kthread_create_worker_on_cpu+0xc0/0xc0
[70013.082592] ret_from_fork+0x1f/0x40
I'm curious how did you get this error? I would expect to see some sort
of lock in upper level which prevents it.
The logical relationship of this error is as follows:
aer_recover_work | ent->work
------------------------------------------------------+---------------------------------
aer_recover_work_func |
|- pcie_do_recovery |
|- report_error_detected |
|- mlx5_pci_err_detected |cmd_work_handler
|- mlx5_enter_error_state | |- cmd_alloc_index
|- enter_error_state | |- lock cmd->alloc_lock
|- mlx5_cmd_flush | |- clear_bit
|- mlx5_cmd_trigger_completions | |- unlock cmd->alloc_lock
|- lock cmd->alloc_lock |
|- vector = ~dev->cmd.vars.bitmask |
|- for_each_set_bit |
|- cmd_ent_get(cmd->ent_arr[i]) (UAF) |
|- unlock cmd->alloc_lock | |- cmd->ent_arr[ent->idx] = ent
The cmd->ent_arr[ent->idx] assignment and the bit clearing are not protected by the cmd->alloc_lock in cmd_work_handler().
Thanks
