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Message-ID: <2025122418-CVE-2022-50726-2f42@gregkh>
Date: Wed, 24 Dec 2025 13:26:25 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50726: net/mlx5: Fix possible use-after-free in async command interface

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

net/mlx5: Fix possible use-after-free in async command interface

mlx5_cmd_cleanup_async_ctx should return only after all its callback
handlers were completed. Before this patch, the below race between
mlx5_cmd_cleanup_async_ctx and mlx5_cmd_exec_cb_handler was possible and
lead to a use-after-free:

1. mlx5_cmd_cleanup_async_ctx is called while num_inflight is 2 (i.e.
   elevated by 1, a single inflight callback).
2. mlx5_cmd_cleanup_async_ctx decreases num_inflight to 1.
3. mlx5_cmd_exec_cb_handler is called, decreases num_inflight to 0 and
   is about to call wake_up().
4. mlx5_cmd_cleanup_async_ctx calls wait_event, which returns
   immediately as the condition (num_inflight == 0) holds.
5. mlx5_cmd_cleanup_async_ctx returns.
6. The caller of mlx5_cmd_cleanup_async_ctx frees the mlx5_async_ctx
   object.
7. mlx5_cmd_exec_cb_handler goes on and calls wake_up() on the freed
   object.

Fix it by syncing using a completion object. Mark it completed when
num_inflight reaches 0.

Trace:

BUG: KASAN: use-after-free in do_raw_spin_lock+0x23d/0x270
Read of size 4 at addr ffff888139cd12f4 by task swapper/5/0

CPU: 5 PID: 0 Comm: swapper/5 Not tainted 6.0.0-rc3_for_upstream_debug_2022_08_30_13_10 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
 <IRQ>
 dump_stack_lvl+0x57/0x7d
 print_report.cold+0x2d5/0x684
 ? do_raw_spin_lock+0x23d/0x270
 kasan_report+0xb1/0x1a0
 ? do_raw_spin_lock+0x23d/0x270
 do_raw_spin_lock+0x23d/0x270
 ? rwlock_bug.part.0+0x90/0x90
 ? __delete_object+0xb8/0x100
 ? lock_downgrade+0x6e0/0x6e0
 _raw_spin_lock_irqsave+0x43/0x60
 ? __wake_up_common_lock+0xb9/0x140
 __wake_up_common_lock+0xb9/0x140
 ? __wake_up_common+0x650/0x650
 ? destroy_tis_callback+0x53/0x70 [mlx5_core]
 ? kasan_set_track+0x21/0x30
 ? destroy_tis_callback+0x53/0x70 [mlx5_core]
 ? kfree+0x1ba/0x520
 ? do_raw_spin_unlock+0x54/0x220
 mlx5_cmd_exec_cb_handler+0x136/0x1a0 [mlx5_core]
 ? mlx5_cmd_cleanup_async_ctx+0x220/0x220 [mlx5_core]
 ? mlx5_cmd_cleanup_async_ctx+0x220/0x220 [mlx5_core]
 mlx5_cmd_comp_handler+0x65a/0x12b0 [mlx5_core]
 ? dump_command+0xcc0/0xcc0 [mlx5_core]
 ? lockdep_hardirqs_on_prepare+0x400/0x400
 ? cmd_comp_notifier+0x7e/0xb0 [mlx5_core]
 cmd_comp_notifier+0x7e/0xb0 [mlx5_core]
 atomic_notifier_call_chain+0xd7/0x1d0
 mlx5_eq_async_int+0x3ce/0xa20 [mlx5_core]
 atomic_notifier_call_chain+0xd7/0x1d0
 ? irq_release+0x140/0x140 [mlx5_core]
 irq_int_handler+0x19/0x30 [mlx5_core]
 __handle_irq_event_percpu+0x1f2/0x620
 handle_irq_event+0xb2/0x1d0
 handle_edge_irq+0x21e/0xb00
 __common_interrupt+0x79/0x1a0
 common_interrupt+0x78/0xa0
 </IRQ>
 <TASK>
 asm_common_interrupt+0x22/0x40
RIP: 0010:default_idle+0x42/0x60
Code: c1 83 e0 07 48 c1 e9 03 83 c0 03 0f b6 14 11 38 d0 7c 04 84 d2 75 14 8b 05 eb 47 22 02 85 c0 7e 07 0f 00 2d e0 9f 48 00 fb f4 <c3> 48 c7 c7 80 08 7f 85 e8 d1 d3 3e fe eb de 66 66 2e 0f 1f 84 00
RSP: 0018:ffff888100dbfdf0 EFLAGS: 00000242
RAX: 0000000000000001 RBX: ffffffff84ecbd48 RCX: 1ffffffff0afe110
RDX: 0000000000000004 RSI: 0000000000000000 RDI: ffffffff835cc9bc
RBP: 0000000000000005 R08: 0000000000000001 R09: ffff88881dec4ac3
R10: ffffed1103bd8958 R11: 0000017d0ca571c9 R12: 0000000000000005
R13: ffffffff84f024e0 R14: 0000000000000000 R15: dffffc0000000000
 ? default_idle_call+0xcc/0x450
 default_idle_call+0xec/0x450
 do_idle+0x394/0x450
 ? arch_cpu_idle_exit+0x40/0x40
 ? do_idle+0x17/0x450
 cpu_startup_entry+0x19/0x20
 start_secondary+0x221/0x2b0
 ? set_cpu_sibling_map+0x2070/0x2070
 secondary_startup_64_no_verify+0xcd/0xdb
 </TASK>

Allocated by task 49502:
 kasan_save_stack+0x1e/0x40
 __kasan_kmalloc+0x81/0xa0
 kvmalloc_node+0x48/0xe0
 mlx5e_bulk_async_init+0x35/0x110 [mlx5_core]
 mlx5e_tls_priv_tx_list_cleanup+0x84/0x3e0 [mlx5_core]
 mlx5e_ktls_cleanup_tx+0x38f/0x760 [mlx5_core]
 mlx5e_cleanup_nic_tx+0xa7/0x100 [mlx5_core]
 mlx5e_detach_netdev+0x1ca/0x2b0 [mlx5_core]
 mlx5e_suspend+0xdb/0x140 [mlx5_core]
 mlx5e_remove+0x89/0x190 [mlx5_core]
 auxiliary_bus_remove+0x52/0x70
 device_release_driver_internal+0x40f/0x650
 driver_detach+0xc1/0x180
 bus_remove_driver+0x125/0x2f0
 auxiliary_driver_unregister+0x16/0x50
 mlx5e_cleanup+0x26/0x30 [mlx5_core]
 cleanup+0xc/0x4e [mlx5_core]
 __x64_sys_delete_module+0x2b5/0x450
 do_syscall_64+0x3d/0x90
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Freed by task 49502:
 kasan_save_stack+0x1e/0x40
 kasan_set_track+0x21/0x30
 kasan_set_free_info+0x20/0x30
 ____kasan_slab_free+0x11d/0x1b0
 kfree+0x1ba/0x520
 mlx5e_tls_priv_tx_list_cleanup+0x2e7/0x3e0 [mlx5_core]
 mlx5e_ktls_cleanup_tx+0x38f/0x760 [mlx5_core]
 mlx5e_cleanup_nic_tx+0xa7/0x100 [mlx5_core]
 mlx5e_detach_netdev+0x1ca/0x2b0 [mlx5_core]
 mlx5e_suspend+0xdb/0x140 [mlx5_core]
 mlx5e_remove+0x89/0x190 [mlx5_core]
 auxiliary_bus_remove+0x52/0x70
 device_release_driver_internal+0x40f/0x650
 driver_detach+0xc1/0x180
 bus_remove_driver+0x125/0x2f0
 auxiliary_driver_unregister+0x16/0x50
 mlx5e_cleanup+0x26/0x30 [mlx5_core]
 cleanup+0xc/0x4e [mlx5_core]
 __x64_sys_delete_module+0x2b5/0x450
 do_syscall_64+0x3d/0x90
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

The Linux kernel CVE team has assigned CVE-2022-50726 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.1 with commit e355477ed9e4f401e3931043df97325d38552d54 and fixed in 5.4.223 with commit 69dd3ad406c49aa69ce4852c15231ac56af8caf9
	Issue introduced in 5.1 with commit e355477ed9e4f401e3931043df97325d38552d54 and fixed in 5.10.153 with commit bbcc06933f35651294ea1e963757502312c2171f
	Issue introduced in 5.1 with commit e355477ed9e4f401e3931043df97325d38552d54 and fixed in 5.15.77 with commit ab3de780c176bb91995c6166a576b370d9726e17
	Issue introduced in 5.1 with commit e355477ed9e4f401e3931043df97325d38552d54 and fixed in 6.0.7 with commit 0aa3ee1e4e5c9ed5dda11249450d609c3072c54e
	Issue introduced in 5.1 with commit e355477ed9e4f401e3931043df97325d38552d54 and fixed in 6.1 with commit bacd22df95147ed673bec4692ab2d4d585935241

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-50726
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/mellanox/mlx5/core/cmd.c
	include/linux/mlx5/driver.h


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/69dd3ad406c49aa69ce4852c15231ac56af8caf9
	https://git.kernel.org/stable/c/bbcc06933f35651294ea1e963757502312c2171f
	https://git.kernel.org/stable/c/ab3de780c176bb91995c6166a576b370d9726e17
	https://git.kernel.org/stable/c/0aa3ee1e4e5c9ed5dda11249450d609c3072c54e
	https://git.kernel.org/stable/c/bacd22df95147ed673bec4692ab2d4d585935241

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