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ubuntucveUbuntu.comUB:CVE-2023-52587
HistoryMar 06, 2024 - 12:00 a.m.

CVE-2023-52587

2024-03-0600:00:00
ubuntu.com
ubuntu.com
7
linux kernel
cve-2023-52587
vulnerability
ib/ipoib
mcast list locking
hard lockup

7.5 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

13.2%

In the Linux kernel, the following vulnerability has been resolved:
IB/ipoib: Fix mcast list locking Releasing the priv->lock while iterating
the priv->multicast_list in ipoib_mcast_join_task() opens a window for
ipoib_mcast_dev_flush() to remove the items while in the middle of
iteration. If the mcast is removed while the lock was dropped, the for loop
spins forever resulting in a hard lockup (as was reported on RHEL
4.18.0-372.75.1.el8_6 kernel): Task A (kworker/u72:2 below) | Task B
(kworker/u72:0 below)
-----------------------------------±----------------------------------
ipoib_mcast_join_task(work) | ipoib_ib_dev_flush_light(work)
spin_lock_irq(&priv->lock) | __ipoib_ib_dev_flush(priv, …)
list_for_each_entry(mcast, | ipoib_mcast_dev_flush(dev = priv->dev)
&priv->multicast_list, list) | ipoib_mcast_join(dev, mcast) |
spin_unlock_irq(&priv->lock) | | spin_lock_irqsave(&priv->lock, flags) |
list_for_each_entry_safe(mcast, tmcast, | &priv->multicast_list, list) |
list_del(&mcast->list); | list_add_tail(&mcast->list, &remove_list) |
spin_unlock_irqrestore(&priv->lock, flags) spin_lock_irq(&priv->lock) | |
ipoib_mcast_remove_list(&remove_list) (Here, mcast is no longer on the |
list_for_each_entry_safe(mcast, tmcast, priv->multicast_list and we keep
| remove_list, list) spinning on the remove_list of | >>>
wait_for_completion(&mcast->done) the other thread which is blocked | and
the list is still valid on | it’s stack.) Fix this by keeping the lock held
and changing to GFP_ATOMIC to prevent eventual sleeps. Unfortunately we
could not reproduce the lockup and confirm this fix but based on the code
review I think this fix should address such lockups. crash> bc 31 PID: 747
TASK: ff1c6a1a007e8000 CPU: 31 COMMAND: “kworker/u72:2” – [exception RIP:
ipoib_mcast_join_task+0x1b1] RIP: ffffffffc0944ac1 RSP: ff646f199a8c7e00
RFLAGS: 00000002 RAX: 0000000000000000 RBX: ff1c6a1a04dc82f8 RCX:
0000000000000000 work (&priv->mcast_task{,.work}) RDX: ff1c6a192d60ac68
RSI: 0000000000000286 RDI: ff1c6a1a04dc8000 &mcast->list RBP:
ff646f199a8c7e90 R8: ff1c699980019420 R9: ff1c6a1920c9a000 R10:
ff646f199a8c7e00 R11: ff1c6a191a7d9800 R12: ff1c6a192d60ac00 mcast R13:
ff1c6a1d82200000 R14: ff1c6a1a04dc8000 R15: ff1c6a1a04dc82d8 dev priv
(&priv->lock) &priv->multicast_list (aka head) ORIG_RAX: ffffffffffffffff
CS: 0010 SS: 0018 — <NMI exception stack> — #5 [ff646f199a8c7e00]
ipoib_mcast_join_task+0x1b1 at ffffffffc0944ac1 [ib_ipoib] #6
[ff646f199a8c7e98] process_one_work+0x1a7 at ffffffff9bf10967 crash> rx
ff646f199a8c7e68 ff646f199a8c7e68: ff1c6a1a04dc82f8 <<< work =
&priv->mcast_task.work crash> list -hO ipoib_dev_priv.multicast_list
ff1c6a1a04dc8000 (empty) crash>
ipoib_dev_priv.mcast_task.work.func,mcast_mutex.owner.counter
ff1c6a1a04dc8000 mcast_task.work.func = 0xffffffffc0944910
<ipoib_mcast_join_task>, mcast_mutex.owner.counter = 0xff1c69998efec000
crash> b 8 PID: 8 TASK: ff1c69998efec000 CPU: 33 COMMAND: “kworker/u72:0”
– #3 [ff646f1980153d50] wait_for_completion+0x96 at ffffffff9c7d7646 #4
[ff646f1980153d90] ipoib_mcast_remove_list+0x56 at ffffffffc0944dc6
[ib_ipoib] #5 [ff646f1980153de8] ipoib_mcast_dev_flush+0x1a7 at
ffffffffc09455a7 [ib_ipoib] #6 [ff646f1980153e58]
__ipoib_ib_dev_flush+0x1a4 at ffffffffc09431a4 [ib_ipoib] #7 [ff
—truncated—

Notes

Author Note
rodrigo-zaiden USN-6765-1 for linux-oem-6.5 wrongly stated that this CVE was fixed in version 6.5.0-1022.23. The mentioned notice was revoked and the state of the fix for linux-oem-6.5 was recovered to the previous state.

References

7.5 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

13.2%