linux-cve-announce - CVE-2024-38588: ftrace: Fix possible use-after-free issue in ftrace

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Message-ID: <2024061950-CVE-2024-38588-f908@gregkh>
Date: Wed, 19 Jun 2024 15:38:00 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-38588: ftrace: Fix possible use-after-free issue in ftrace_location()

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

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

ftrace: Fix possible use-after-free issue in ftrace_location()

KASAN reports a bug:

  BUG: KASAN: use-after-free in ftrace_location+0x90/0x120
  Read of size 8 at addr ffff888141d40010 by task insmod/424
  CPU: 8 PID: 424 Comm: insmod Tainted: G        W          6.9.0-rc2+
  [...]
  Call Trace:
   <TASK>
   dump_stack_lvl+0x68/0xa0
   print_report+0xcf/0x610
   kasan_report+0xb5/0xe0
   ftrace_location+0x90/0x120
   register_kprobe+0x14b/0xa40
   kprobe_init+0x2d/0xff0 [kprobe_example]
   do_one_initcall+0x8f/0x2d0
   do_init_module+0x13a/0x3c0
   load_module+0x3082/0x33d0
   init_module_from_file+0xd2/0x130
   __x64_sys_finit_module+0x306/0x440
   do_syscall_64+0x68/0x140
   entry_SYSCALL_64_after_hwframe+0x71/0x79

The root cause is that, in lookup_rec(), ftrace record of some address
is being searched in ftrace pages of some module, but those ftrace pages
at the same time is being freed in ftrace_release_mod() as the
corresponding module is being deleted:

           CPU1                       |      CPU2
  register_kprobes() {                | delete_module() {
    check_kprobe_address_safe() {     |
      arch_check_ftrace_location() {  |
        ftrace_location() {           |
          lookup_rec() // USE!        |   ftrace_release_mod() // Free!

To fix this issue:
  1. Hold rcu lock as accessing ftrace pages in ftrace_location_range();
  2. Use ftrace_location_range() instead of lookup_rec() in
     ftrace_location();
  3. Call synchronize_rcu() before freeing any ftrace pages both in
     ftrace_process_locs()/ftrace_release_mod()/ftrace_free_mem().

The Linux kernel CVE team has assigned CVE-2024-38588 to this issue.


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

	Issue introduced in 3.7 with commit ae6aa16fdc16 and fixed in 6.1.93 with commit dbff5f0bfb24
	Issue introduced in 3.7 with commit ae6aa16fdc16 and fixed in 6.6.33 with commit 7b4881da5b19
	Issue introduced in 3.7 with commit ae6aa16fdc16 and fixed in 6.8.12 with commit 66df065b3106
	Issue introduced in 3.7 with commit ae6aa16fdc16 and fixed in 6.9.3 with commit 31310e373f4c
	Issue introduced in 3.7 with commit ae6aa16fdc16 and fixed in 6.10-rc1 with commit e60b613df8b6

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-2024-38588
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:
	kernel/trace/ftrace.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/dbff5f0bfb2416b8b55c105ddbcd4f885e98fada
	https://git.kernel.org/stable/c/7b4881da5b19f65709f5c18c1a4d8caa2e496461
	https://git.kernel.org/stable/c/66df065b3106964e667b37bf8f7e55ec69d0c1f6
	https://git.kernel.org/stable/c/31310e373f4c8c74e029d4326b283e757edabc0b
	https://git.kernel.org/stable/c/e60b613df8b6253def41215402f72986fee3fc8d