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Message-ID: <2024052430-CVE-2021-47512-4d70@gregkh>
Date: Fri, 24 May 2024 17:09:32 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2021-47512: net/sched: fq_pie: prevent dismantle issue
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
net/sched: fq_pie: prevent dismantle issue
For some reason, fq_pie_destroy() did not copy
working code from pie_destroy() and other qdiscs,
thus causing elusive bug.
Before calling del_timer_sync(&q->adapt_timer),
we need to ensure timer will not rearm itself.
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (4416 ticks this GP) idle=60d/1/0x4000000000000000 softirq=10433/10434 fqs=2579
(t=10501 jiffies g=13085 q=3989)
NMI backtrace for cpu 0
CPU: 0 PID: 13 Comm: ksoftirqd/0 Not tainted 5.16.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
rcu_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:343
print_cpu_stall kernel/rcu/tree_stall.h:627 [inline]
check_cpu_stall kernel/rcu/tree_stall.h:711 [inline]
rcu_pending kernel/rcu/tree.c:3878 [inline]
rcu_sched_clock_irq.cold+0x9d/0x746 kernel/rcu/tree.c:2597
update_process_times+0x16d/0x200 kernel/time/timer.c:1785
tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226
tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1428
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline]
__sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103
sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:write_comp_data kernel/kcov.c:221 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp1+0x1d/0x80 kernel/kcov.c:273
Code: 54 c8 20 48 89 10 c3 66 0f 1f 44 00 00 53 41 89 fb 41 89 f1 bf 03 00 00 00 65 48 8b 0c 25 40 70 02 00 48 89 ce 4c 8b 54 24 08 <e8> 4e f7 ff ff 84 c0 74 51 48 8b 81 88 15 00 00 44 8b 81 84 15 00
RSP: 0018:ffffc90000d27b28 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888064bf1bf0 RCX: ffff888011928000
RDX: ffff888011928000 RSI: ffff888011928000 RDI: 0000000000000003
RBP: ffff888064bf1c28 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff875d8295 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8880783dd300 R14: 0000000000000000 R15: 0000000000000000
pie_calculate_probability+0x405/0x7c0 net/sched/sch_pie.c:418
fq_pie_timer+0x170/0x2a0 net/sched/sch_fq_pie.c:383
call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
expire_timers kernel/time/timer.c:1466 [inline]
__run_timers.part.0+0x675/0xa20 kernel/time/timer.c:1734
__run_timers kernel/time/timer.c:1715 [inline]
run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558
run_ksoftirqd kernel/softirq.c:921 [inline]
run_ksoftirqd+0x2d/0x60 kernel/softirq.c:913
smpboot_thread_fn+0x645/0x9c0 kernel/smpboot.c:164
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
The Linux kernel CVE team has assigned CVE-2021-47512 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.6 with commit ec97ecf1ebe4 and fixed in 5.10.85 with commit 2a51edaf5cc5
Issue introduced in 5.6 with commit ec97ecf1ebe4 and fixed in 5.15.8 with commit d86216dfda7c
Issue introduced in 5.6 with commit ec97ecf1ebe4 and fixed in 5.16 with commit 61c2402665f1
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-2021-47512
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:
net/sched/sch_fq_pie.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/2a51edaf5cc563574878b93d7ef3d5955dda7030
https://git.kernel.org/stable/c/d86216dfda7c98375f809e26a30bfdaaba21d46e
https://git.kernel.org/stable/c/61c2402665f1e10c5742033fce18392e369931d7
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