linux-cve-announce - CVE-2024-50126: net: sched: use RCU read-side critical section in taprio

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Message-ID: <2024110557-CVE-2024-50126-733b@gregkh>
Date: Tue,  5 Nov 2024 18:11:15 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-50126: net: sched: use RCU read-side critical section in taprio_dump()

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

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

net: sched: use RCU read-side critical section in taprio_dump()

Fix possible use-after-free in 'taprio_dump()' by adding RCU
read-side critical section there. Never seen on x86 but
found on a KASAN-enabled arm64 system when investigating
https://syzkaller.appspot.com/bug?extid=b65e0af58423fc8a73aa:

[T15862] BUG: KASAN: slab-use-after-free in taprio_dump+0xa0c/0xbb0
[T15862] Read of size 4 at addr ffff0000d4bb88f8 by task repro/15862
[T15862]
[T15862] CPU: 0 UID: 0 PID: 15862 Comm: repro Not tainted 6.11.0-rc1-00293-gdefaf1a2113a-dirty #2
[T15862] Hardware name: QEMU QEMU Virtual Machine, BIOS edk2-20240524-5.fc40 05/24/2024
[T15862] Call trace:
[T15862]  dump_backtrace+0x20c/0x220
[T15862]  show_stack+0x2c/0x40
[T15862]  dump_stack_lvl+0xf8/0x174
[T15862]  print_report+0x170/0x4d8
[T15862]  kasan_report+0xb8/0x1d4
[T15862]  __asan_report_load4_noabort+0x20/0x2c
[T15862]  taprio_dump+0xa0c/0xbb0
[T15862]  tc_fill_qdisc+0x540/0x1020
[T15862]  qdisc_notify.isra.0+0x330/0x3a0
[T15862]  tc_modify_qdisc+0x7b8/0x1838
[T15862]  rtnetlink_rcv_msg+0x3c8/0xc20
[T15862]  netlink_rcv_skb+0x1f8/0x3d4
[T15862]  rtnetlink_rcv+0x28/0x40
[T15862]  netlink_unicast+0x51c/0x790
[T15862]  netlink_sendmsg+0x79c/0xc20
[T15862]  __sock_sendmsg+0xe0/0x1a0
[T15862]  ____sys_sendmsg+0x6c0/0x840
[T15862]  ___sys_sendmsg+0x1ac/0x1f0
[T15862]  __sys_sendmsg+0x110/0x1d0
[T15862]  __arm64_sys_sendmsg+0x74/0xb0
[T15862]  invoke_syscall+0x88/0x2e0
[T15862]  el0_svc_common.constprop.0+0xe4/0x2a0
[T15862]  do_el0_svc+0x44/0x60
[T15862]  el0_svc+0x50/0x184
[T15862]  el0t_64_sync_handler+0x120/0x12c
[T15862]  el0t_64_sync+0x190/0x194
[T15862]
[T15862] Allocated by task 15857:
[T15862]  kasan_save_stack+0x3c/0x70
[T15862]  kasan_save_track+0x20/0x3c
[T15862]  kasan_save_alloc_info+0x40/0x60
[T15862]  __kasan_kmalloc+0xd4/0xe0
[T15862]  __kmalloc_cache_noprof+0x194/0x334
[T15862]  taprio_change+0x45c/0x2fe0
[T15862]  tc_modify_qdisc+0x6a8/0x1838
[T15862]  rtnetlink_rcv_msg+0x3c8/0xc20
[T15862]  netlink_rcv_skb+0x1f8/0x3d4
[T15862]  rtnetlink_rcv+0x28/0x40
[T15862]  netlink_unicast+0x51c/0x790
[T15862]  netlink_sendmsg+0x79c/0xc20
[T15862]  __sock_sendmsg+0xe0/0x1a0
[T15862]  ____sys_sendmsg+0x6c0/0x840
[T15862]  ___sys_sendmsg+0x1ac/0x1f0
[T15862]  __sys_sendmsg+0x110/0x1d0
[T15862]  __arm64_sys_sendmsg+0x74/0xb0
[T15862]  invoke_syscall+0x88/0x2e0
[T15862]  el0_svc_common.constprop.0+0xe4/0x2a0
[T15862]  do_el0_svc+0x44/0x60
[T15862]  el0_svc+0x50/0x184
[T15862]  el0t_64_sync_handler+0x120/0x12c
[T15862]  el0t_64_sync+0x190/0x194
[T15862]
[T15862] Freed by task 6192:
[T15862]  kasan_save_stack+0x3c/0x70
[T15862]  kasan_save_track+0x20/0x3c
[T15862]  kasan_save_free_info+0x4c/0x80
[T15862]  poison_slab_object+0x110/0x160
[T15862]  __kasan_slab_free+0x3c/0x74
[T15862]  kfree+0x134/0x3c0
[T15862]  taprio_free_sched_cb+0x18c/0x220
[T15862]  rcu_core+0x920/0x1b7c
[T15862]  rcu_core_si+0x10/0x1c
[T15862]  handle_softirqs+0x2e8/0xd64
[T15862]  __do_softirq+0x14/0x20

The Linux kernel CVE team has assigned CVE-2024-50126 to this issue.


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

	Issue introduced in 6.1 with commit 18cdd2f0998a and fixed in 6.6.59 with commit 5d282467245f
	Issue introduced in 6.1 with commit 18cdd2f0998a and fixed in 6.11.6 with commit e4369cb6acf6
	Issue introduced in 6.1 with commit 18cdd2f0998a and fixed in 6.12-rc5 with commit b22db8b8befe

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-2024-50126
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_taprio.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/5d282467245f267c0b9ada3f7f309ff838521536
	https://git.kernel.org/stable/c/e4369cb6acf6b895ac2453cc1cdf2f4326122c6d
	https://git.kernel.org/stable/c/b22db8b8befe90b61c98626ca1a2fbb0505e9fe3