[PATCH -rc] workqueue: Reimplement UAF fix to avoid lockdep worning

Leon Romanovsky
2024-05-28T08:40:15Z

From: Leon Romanovsky <leonro@nvidia.com>

The commit 643445531829 ("workqueue: Fix UAF report by KASAN in
pwq_release_workfn()") causes to the following lockdep warning.

[ 1818.839405] ==================================================================
[ 1818.840636] BUG: KASAN: slab-use-after-free in lockdep_register_key+0x707/0x810
[ 1818.841827] Read of size 8 at addr ffff888156864928 by task systemd-udevd/71399
[ 1818.843007]
[ 1818.843378] CPU: 8 PID: 71399 Comm: systemd-udevd Not tainted 6.10.0-rc1_external_1613e604df0c #1
[ 1818.844806] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 1818.846493] Call Trace:
[ 1818.846981] <TASK>
[ 1818.847439] dump_stack_lvl+0x7e/0xc0
[ 1818.848089] print_report+0xc1/0x600
[ 1818.848728] ? __virt_addr_valid+0x1cf/0x390
[ 1818.849458] ? lockdep_register_key+0x707/0x810
[ 1818.850221] ? lockdep_register_key+0x707/0x810
[ 1818.850978] kasan_report+0xb9/0xf0
[ 1818.851604] ? lockdep_register_key+0x707/0x810
[ 1818.852381] lockdep_register_key+0x707/0x810
[ 1818.853121] ? add_lock_to_list+0x5b0/0x5b0
[ 1818.853842] ? lockdep_init_map_type+0x2c3/0x7a0
[ 1818.854594] ? __raw_spin_lock_init+0x3b/0x110
[ 1818.855329] alloc_workqueue+0x466/0x1800
[ 1818.856005] ? pointer+0x8a0/0x8a0
[ 1818.856615] ? workqueue_sysfs_register+0x370/0x370
[ 1818.857399] ? vsprintf+0x10/0x10
[ 1818.857997] ib_mad_init_device+0x809/0x1760 [ib_core]
[ 1818.858893] ? ib_mad_post_receive_mads+0xf20/0xf20 [ib_core]
[ 1818.859809] ? rwsem_mark_wake+0x990/0x990
[ 1818.860505] ? do_raw_spin_unlock+0x54/0x220
[ 1818.861224] add_client_context+0x2e9/0x430 [ib_core]
[ 1818.862058] ? ib_unregister_driver+0x1a0/0x1a0 [ib_core]
[ 1818.862933] enable_device_and_get+0x1a7/0x340 [ib_core]
[ 1818.863788] ? add_client_context+0x430/0x430 [ib_core]
[ 1818.864643] ? rdma_counter_init+0x139/0x390 [ib_core]
[ 1818.865487] ib_register_device+0x6d0/0xa60 [ib_core]
[ 1818.866320] ? alloc_port_data.part.0+0x390/0x390 [ib_core]
[ 1818.867212] ? mlx5_lag_is_active+0x7c/0xb0 [mlx5_core]
[ 1818.868204] __mlx5_ib_add+0x88/0x1e0 [mlx5_ib]
[ 1818.868989] mlx5r_probe+0x1d0/0x3c0 [mlx5_ib]
[ 1818.869744] ? __mlx5_ib_add+0x1e0/0x1e0 [mlx5_ib]
[ 1818.870542] auxiliary_bus_probe+0xa1/0x110
[ 1818.871234] really_probe+0x1e4/0x920
[ 1818.871862] __driver_probe_device+0x261/0x3e0
[ 1818.872609] driver_probe_device+0x49/0x130
[ 1818.873311] __driver_attach+0x215/0x4c0
[ 1818.873969] ? __device_attach_driver+0x290/0x290
[ 1818.874726] bus_for_each_dev+0xf0/0x170
[ 1818.875392] ? lockdep_init_map_type+0x2c3/0x7a0
[ 1818.876151] ? bus_remove_file+0x40/0x40
[ 1818.876820] bus_add_driver+0x21d/0x5d0
[ 1818.877472] driver_register+0x133/0x460
[ 1818.878138] __auxiliary_driver_register+0x14e/0x230
[ 1818.878930] ? 0xffffffffa07f8000
[ 1818.879516] ? 0xffffffffa07f8000
[ 1818.880110] mlx5_ib_init+0x111/0x190 [mlx5_ib]
[ 1818.880879] do_one_initcall+0xc4/0x3c0
[ 1818.881532] ? trace_event_raw_event_initcall_level+0x1f0/0x1f0
[ 1818.882447] ? __create_object+0x5e/0x80
[ 1818.883115] ? kmalloc_trace_noprof+0x1f9/0x410
[ 1818.883860] ? kasan_unpoison+0x23/0x50
[ 1818.884520] do_init_module+0x22d/0x740
[ 1818.885184] load_module+0x5077/0x6690
[ 1818.885839] ? module_frob_arch_sections+0x20/0x20
[ 1818.886618] ? kernel_read_file+0x560/0x6c0
[ 1818.887311] ? kernel_read_file+0x246/0x6c0
[ 1818.888005] ? __x64_sys_fsopen+0x190/0x190
[ 1818.888708] ? expand_stack+0x440/0x440
[ 1818.889367] ? init_module_from_file+0xd2/0x130
[ 1818.890102] init_module_from_file+0xd2/0x130
[ 1818.890824] ? __x64_sys_init_module+0xb0/0xb0
[ 1818.891558] ? do_raw_spin_unlock+0x54/0x220
[ 1818.892291] idempotent_init_module+0x326/0x5a0
[ 1818.893030] ? init_module_from_file+0x130/0x130
[ 1818.893783] ? security_capable+0x51/0x90
[ 1818.894461] __x64_sys_finit_module+0xc1/0x130
[ 1818.895192] do_syscall_64+0x6d/0x140
[ 1818.895818] entry_SYSCALL_64_after_hwframe+0x4b/0x53
[ 1818.896631] RIP: 0033:0x7f29a2b0af3d
[ 1818.897254] Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa
48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f
05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d bb ee 0e 00 f7 d8 64 89 01 48
[ 1818.899904] RSP: 002b:00007ffc9cd4cda8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[ 1818.901092] RAX: ffffffffffffffda RBX: 00005643c8995670 RCX: 00007f29a2b0af3d
[ 1818.902157] RDX: 0000000000000000 RSI: 00007f29a31ef32c RDI: 0000000000000011
[ 1818.903224] RBP: 0000000000020000 R08: 0000000000000000 R09: 0000000000000002
[ 1818.904292] R10: 0000000000000011 R11: 0000000000000246 R12: 00007f29a31ef32c
[ 1818.905365] R13: 00005643c89efca0 R14: 0000000000000007 R15: 00005643c8993530
[ 1818.906431] </TASK>
[ 1818.906877]
[ 1818.907242] Allocated by task 1:
[ 1818.907819] kasan_save_stack+0x20/0x40
[ 1818.908512] kasan_save_track+0x10/0x30
[ 1818.909173] __kasan_slab_alloc+0x51/0x60
[ 1818.909849] kmem_cache_alloc_noprof+0x139/0x3f0
[ 1818.910608] getname_flags+0x4f/0x3c0
[ 1818.911236] do_sys_openat2+0xd3/0x150
[ 1818.911878] __x64_sys_openat+0x11f/0x1d0
[ 1818.912554] do_syscall_64+0x6d/0x140
[ 1818.913189] entry_SYSCALL_64_after_hwframe+0x4b/0x53
[ 1818.913996]
[ 1818.914359] Freed by task 1:
[ 1818.914897] kasan_save_stack+0x20/0x40
[ 1818.915553] kasan_save_track+0x10/0x30
[ 1818.916210] kasan_save_free_info+0x37/0x50
[ 1818.916911] poison_slab_object+0x10c/0x190
[ 1818.917606] __kasan_slab_free+0x11/0x30
[ 1818.918271] kmem_cache_free+0x12c/0x460
[ 1818.918939] do_sys_openat2+0x102/0x150
[ 1818.919586] __x64_sys_openat+0x11f/0x1d0
[ 1818.920264] do_syscall_64+0x6d/0x140
[ 1818.920899] entry_SYSCALL_64_after_hwframe+0x4b/0x53
[ 1818.921699]
[ 1818.922059] The buggy address belongs to the object at ffff888156864400
[ 1818.922059] which belongs to the cache names_cache of size 4096
[ 1818.923872] The buggy address is located 1320 bytes inside of
[ 1818.923872] freed 4096-byte region [ffff888156864400, ffff888156865400)
[ 1818.925674]
[ 1818.926034] The buggy address belongs to the physical page:
[ 1818.926905] page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x156860
[ 1818.928155] head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
[ 1818.929358] flags: 0x200000000000040(head|node=0|zone=2)
[ 1818.930195] page_type: 0xffffefff(slab)
[ 1818.930844] raw: 0200000000000040 ffff8881009ab040 dead000000000122 0000000000000000
[ 1818.932049] raw: 0000000000000000 0000000000070007 00000001ffffefff 0000000000000000
[ 1818.933277] head: 0200000000000040 ffff8881009ab040 dead000000000122 0000000000000000
[ 1818.934506] head: 0000000000000000 0000000000070007 00000001ffffefff 0000000000000000
[ 1818.935728] head: 0200000000000003 ffffea00055a1801 ffffffffffffffff 0000000000000000
[ 1818.936962] head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
[ 1818.938186] page dumped because: kasan: bad access detected
[ 1818.939065]
[ 1818.939429] Memory state around the buggy address:
[ 1818.940197] ffff888156864800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1818.941358] ffff888156864880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1818.942504] >ffff888156864900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1818.943656] ^
[ 1818.944399] ffff888156864980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1818.945564] ffff888156864a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 1818.946711] ==================================================================

As a solution, let's rewrite the commit mentioned in Fixes line to
properly unwind error without need to flash anything.

Fixes: 643445531829 ("workqueue: Fix UAF report by KASAN in pwq_release_workfn()")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
kernel/workqueue.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 003474c9a77d..c3df0a1f908b 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5454,7 +5454,7 @@ static void wq_update_pod(struct workqueue_struct *wq, int cpu,
static int alloc_and_link_pwqs(struct workqueue_struct *wq)
{
bool highpri = wq->flags & WQ_HIGHPRI;
- int cpu, ret;
+ int cpu, ret = -ENOMEM;

wq->cpu_pwq = alloc_percpu(struct pool_workqueue *);
if (!wq->cpu_pwq)
@@ -5502,14 +5502,10 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq)
ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
}
cpus_read_unlock();
-
- /* for unbound pwq, flush the pwq_release_worker ensures that the
- * pwq_release_workfn() completes before calling kfree(wq).
- */
if (ret)
- kthread_flush_worker(pwq_release_worker);
+ goto enomem;

- return ret;
+ return 0;

enomem:
if (wq->cpu_pwq) {
@@ -5522,7 +5518,7 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq)
free_percpu(wq->cpu_pwq);
wq->cpu_pwq = NULL;
}
- return -ENOMEM;
+ return ret;
}

static int wq_clamp_max_active(int max_active, unsigned int flags,
@@ -5714,7 +5710,7 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
goto err_unreg_lockdep;
}

- if (alloc_and_link_pwqs(wq) < 0)
+ if (alloc_and_link_pwqs(wq))
goto err_free_node_nr_active;

if (wq_online && init_rescuer(wq) < 0)
--
2.45.1