Date: Wed,  3 Apr 2024 16:56:15 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-26724: net/mlx5: DPLL, Fix possible use after free after delayed work timer triggers

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

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

net/mlx5: DPLL, Fix possible use after free after delayed work timer triggers

I managed to hit following use after free warning recently:

[ 2169.711665] ==================================================================
[ 2169.714009] BUG: KASAN: slab-use-after-free in __run_timers.part.0+0x179/0x4c0
[ 2169.716293] Write of size 8 at addr ffff88812b326a70 by task swapper/4/0

[ 2169.719022] CPU: 4 PID: 0 Comm: swapper/4 Not tainted 6.8.0-rc2jiri+ #2
[ 2169.720974] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 2169.722457] Call Trace:
[ 2169.722756]  <IRQ>
[ 2169.723024]  dump_stack_lvl+0x58/0xb0
[ 2169.723417]  print_report+0xc5/0x630
[ 2169.723807]  ? __virt_addr_valid+0x126/0x2b0
[ 2169.724268]  kasan_report+0xbe/0xf0
[ 2169.724667]  ? __run_timers.part.0+0x179/0x4c0
[ 2169.725116]  ? __run_timers.part.0+0x179/0x4c0
[ 2169.725570]  __run_timers.part.0+0x179/0x4c0
[ 2169.726003]  ? call_timer_fn+0x320/0x320
[ 2169.726404]  ? lock_downgrade+0x3a0/0x3a0
[ 2169.726820]  ? kvm_clock_get_cycles+0x14/0x20
[ 2169.727257]  ? ktime_get+0x92/0x150
[ 2169.727630]  ? lapic_next_deadline+0x35/0x60
[ 2169.728069]  run_timer_softirq+0x40/0x80
[ 2169.728475]  __do_softirq+0x1a1/0x509
[ 2169.728866]  irq_exit_rcu+0x95/0xc0
[ 2169.729241]  sysvec_apic_timer_interrupt+0x6b/0x80
[ 2169.729718]  </IRQ>
[ 2169.729993]  <TASK>
[ 2169.730259]  asm_sysvec_apic_timer_interrupt+0x16/0x20
[ 2169.730755] RIP: 0010:default_idle+0x13/0x20
[ 2169.731190] Code: c0 08 00 00 00 4d 29 c8 4c 01 c7 4c 29 c2 e9 72 ff ff ff cc cc cc cc 8b 05 9a 7f 1f 02 85 c0 7e 07 0f 00 2d cf 69 43 00 fb f4 <fa> c3 66 66 2e 0f 1f 84 00 00 00 00 00 65 48 8b 04 25 c0 93 04 00
[ 2169.732759] RSP: 0018:ffff888100dbfe10 EFLAGS: 00000242
[ 2169.733264] RAX: 0000000000000001 RBX: ffff888100d9c200 RCX: ffffffff8241bd62
[ 2169.733925] RDX: ffffed109a848b15 RSI: 0000000000000004 RDI: ffffffff8127ac55
[ 2169.734566] RBP: 0000000000000004 R08: 0000000000000000 R09: ffffed109a848b14
[ 2169.735200] R10: ffff8884d42458a3 R11: 000000000000ba7e R12: ffffffff83d7d3a0
[ 2169.735835] R13: 1ffff110201b7fc6 R14: 0000000000000000 R15: ffff888100d9c200
[ 2169.736478]  ? ct_kernel_exit.constprop.0+0xa2/0xc0
[ 2169.736954]  ? do_idle+0x285/0x290
[ 2169.737323]  default_idle_call+0x63/0x90
[ 2169.737730]  do_idle+0x285/0x290
[ 2169.738089]  ? arch_cpu_idle_exit+0x30/0x30
[ 2169.738511]  ? mark_held_locks+0x1a/0x80
[ 2169.738917]  ? lockdep_hardirqs_on_prepare+0x12e/0x200
[ 2169.739417]  cpu_startup_entry+0x30/0x40
[ 2169.739825]  start_secondary+0x19a/0x1c0
[ 2169.740229]  ? set_cpu_sibling_map+0xbd0/0xbd0
[ 2169.740673]  secondary_startup_64_no_verify+0x15d/0x16b
[ 2169.741179]  </TASK>

[ 2169.741686] Allocated by task 1098:
[ 2169.742058]  kasan_save_stack+0x1c/0x40
[ 2169.742456]  kasan_save_track+0x10/0x30
[ 2169.742852]  __kasan_kmalloc+0x83/0x90
[ 2169.743246]  mlx5_dpll_probe+0xf5/0x3c0 [mlx5_dpll]
[ 2169.743730]  auxiliary_bus_probe+0x62/0xb0
[ 2169.744148]  really_probe+0x127/0x590
[ 2169.744534]  __driver_probe_device+0xd2/0x200
[ 2169.744973]  device_driver_attach+0x6b/0xf0
[ 2169.745402]  bind_store+0x90/0xe0
[ 2169.745761]  kernfs_fop_write_iter+0x1df/0x2a0
[ 2169.746210]  vfs_write+0x41f/0x790
[ 2169.746579]  ksys_write+0xc7/0x160
[ 2169.746947]  do_syscall_64+0x6f/0x140
[ 2169.747333]  entry_SYSCALL_64_after_hwframe+0x46/0x4e

[ 2169.748049] Freed by task 1220:
[ 2169.748393]  kasan_save_stack+0x1c/0x40
[ 2169.748789]  kasan_save_track+0x10/0x30
[ 2169.749188]  kasan_save_free_info+0x3b/0x50
[ 2169.749621]  poison_slab_object+0x106/0x180
[ 2169.750044]  __kasan_slab_free+0x14/0x50
[ 2169.750451]  kfree+0x118/0x330
[ 2169.750792]  mlx5_dpll_remove+0xf5/0x110 [mlx5_dpll]
[ 2169.751271]  auxiliary_bus_remove+0x2e/0x40
[ 2169.751694]  device_release_driver_internal+0x24b/0x2e0
[ 2169.752191]  unbind_store+0xa6/0xb0
[ 2169.752563]  kernfs_fop_write_iter+0x1df/0x2a0
[ 2169.753004]  vfs_write+0x41f/0x790
[ 2169.753381]  ksys_write+0xc7/0x160
[ 2169.753750]  do_syscall_64+0x6f/0x140
[ 2169.754132]  entry_SYSCALL_64_after_hwframe+0x46/0x4e

[ 2169.754847] Last potentially related work creation:
[ 2169.755315]  kasan_save_stack+0x1c/0x40
[ 2169.755709]  __kasan_record_aux_stack+0x9b/0xf0
[ 2169.756165]  __queue_work+0x382/0x8f0
[ 2169.756552]  call_timer_fn+0x126/0x320
[ 2169.756941]  __run_timers.part.0+0x2ea/0x4c0
[ 2169.757376]  run_timer_softirq+0x40/0x80
[ 2169.757782]  __do_softirq+0x1a1/0x509

[ 2169.758387] Second to last potentially related work creation:
[ 2169.758924]  kasan_save_stack+0x1c/0x40
[ 2169.759322]  __kasan_record_aux_stack+0x9b/0xf0
[ 2169.759773]  __queue_work+0x382/0x8f0
[ 2169.760156]  call_timer_fn+0x126/0x320
[ 2169.760550]  __run_timers.part.0+0x2ea/0x4c0
[ 2169.760978]  run_timer_softirq+0x40/0x80
[ 2169.761381]  __do_softirq+0x1a1/0x509

[ 2169.761998] The buggy address belongs to the object at ffff88812b326a00
                which belongs to the cache kmalloc-256 of size 256
[ 2169.763061] The buggy address is located 112 bytes inside of
                freed 256-byte region [ffff88812b326a00, ffff88812b326b00)

[ 2169.764346] The buggy address belongs to the physical page:
[ 2169.764866] page:000000000f2b1e89 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12b324
[ 2169.765731] head:000000000f2b1e89 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0
[ 2169.766484] anon flags: 0x200000000000840(slab|head|node=0|zone=2)
[ 2169.767048] page_type: 0xffffffff()
[ 2169.767422] raw: 0200000000000840 ffff888100042b40 0000000000000000 dead000000000001
[ 2169.768183] raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
[ 2169.768899] page dumped because: kasan: bad access detected

[ 2169.769649] Memory state around the buggy address:
[ 2169.770116]  ffff88812b326900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 2169.770805]  ffff88812b326980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 2169.771485] >ffff88812b326a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2169.772173]                                                              ^
[ 2169.772787]  ffff88812b326a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2169.773477]  ffff88812b326b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 2169.774160] ==================================================================
[ 2169.774845] ==================================================================

I didn't manage to reproduce it. Though the issue seems to be obvious.
There is a chance that the mlx5_dpll_remove() calls
cancel_delayed_work() when the work runs and manages to re-arm itself.
In that case, after delay timer triggers next attempt to queue it,
it works with freed memory.

Fix this by using cancel_delayed_work_sync() instead which makes sure
that work is done when it returns.

The Linux kernel CVE team has assigned CVE-2024-26724 to this issue.


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

	Issue introduced in 6.7 with commit 496fd0a26bbf and fixed in 6.7.6 with commit 1596126ea502
	Issue introduced in 6.7 with commit 496fd0a26bbf and fixed in 6.8 with commit aa1eec2f546f

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-2024-26724
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/dpll.c


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/1596126ea50228f0ed96697bae4e9368fda02c56
	https://git.kernel.org/stable/c/aa1eec2f546f2afa8c98ec41e5d8ee488165d685

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