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Bug 1985904 - use-after-free in audit_krule_to_data
Summary: use-after-free in audit_krule_to_data
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: kernel
Version: unspecified
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: beta
: 9.0
Assignee: Richard Guy Briggs
QA Contact: Linqing Lu
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2021-07-26 08:07 UTC by Seiji Nishikawa
Modified: 2024-12-20 20:32 UTC (History)
4 users (show)

Fixed In Version: kernel-5.14.0-12.el9
Doc Type: No Doc Update
Doc Text:
Clone Of:
Environment:
Last Closed: 2022-05-17 15:38:51 UTC
Type: Bug
Target Upstream Version:
Embargoed:
pm-rhel: mirror+

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Gitlab redhat/centos-stream/src/kernel centos-stream-9 merge_requests 81 0 None None None 2021-10-19 16:17:59 UTC
Red Hat Knowledge Base (Solution) 6305751 0 None None None 2021-09-03 08:44:04 UTC
Red Hat Product Errata RHBA-2022:3907 0 None None None 2022-05-17 15:39:16 UTC

Description Seiji Nishikawa 2021-07-26 08:07:34 UTC 
Description of problem:

use-after-free in audit_krule_to_data

Version-Release number of selected component (if applicable):


How reproducible:

Always

Steps to Reproduce:

1. Install 5.14.0-0.rc2.23.el9.x86_64+debug

2. Add the audit rules listed below and reboot

~~~
-a always,exit -F arch=b32 -S adjtimex,settimeofday,stime -F key=time-change
-a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=time-change
-a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -F key=time-change
-a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -F key=time-change
-w /etc/localtime -p wa -k time-change
-w /etc/group -p wa -k identity
-w /etc/passwd -p wa -k identity
-w /etc/gshadow -p wa -k identity
-w /etc/shadow -p wa -k identity
-w /etc/security/opasswd -p wa -k identity
-a always,exit -F arch=b32 -S sethostname,setdomainname -F key=system-locale
-a always,exit -F arch=b64 -S sethostname,setdomainname -F key=system-locale
-w /etc/issue -p wa -k system-locale
-w /etc/issuessh -p wa -k system-locale
-w /etc/issue.net -p wa -k system-locale
-w /etc/hosts -p wa -k system-locale
-w /etc/hostname -p wa -k system-locale
-a always,exit -F dir=/etc/NetworkManager/ -F perm=wa -F key=system-locale
-a always,exit -F dir=/etc/selinux/ -F perm=wa -F key=MAC-policy
-w /var/log/tallylog -p wa -k logins
-w /var/run/faillock/ -p wa -k logins
-w /var/log/lastlog -p wa -k logins
-w /var/run/utmp -p wa -k session
-w /var/log/btmp -p wa -k session
-w /var/log/wtmp -p wa -k session
-a always,exit -F arch=b32 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=unset -F key=perm_mod
-a always,exit -F arch=b64 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=unset -F key=perm_mod
-a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F auid>=1000 -F auid!=unset -F key=perm_mod
-a always,exit -F arch=b64 -S chown,fchown,lchown,fchownat -F auid>=1000 -F auid!=unset -F key=perm_mod
-a always,exit -F arch=b32 -S setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod
-a always,exit -F arch=b64 -S setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod
-a always,exit -F arch=b32 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access
-a always,exit -F arch=b32 -S open,creat,truncate,ftruncate,openat,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access
-a always,exit -F arch=b64 -S open,truncate,ftruncate,creat,openat,open_by_handle_at -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access
-a always,exit -F arch=b64 -S open,truncate,ftruncate,creat,openat,open_by_handle_at -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access
-a always,exit -F arch=b32 -S mount -F auid>=1000 -F auid!=unset -F key=export
-a always,exit -F arch=b64 -S mount -F auid>=1000 -F auid!=unset -F key=export
-a always,exit -F arch=b32 -S unlink,unlinkat,rename,renameat -F auid>=1000 -F auid!=unset -F key=delete
-a always,exit -F arch=b64 -S unlink,unlinkat,rename,renameat -F auid>=1000 -F auid!=unset -F key=delete
-w /etc/sudoers -p wa -k actions
-w /etc/sudoers -p wa -k scope
-w /etc/sudoers.d/ -p wa -k actions
-w /etc/sudoers.d/ -p wa -k scope
find /usr/bin -type f -perm -04000 2>/dev/null | awk '{ printf "-a always,exit -F path=%s -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged\n", $1 }' >> priv.rules
find /usr/sbin -type f -perm -04000 2>/dev/null | awk '{ printf "-a always,exit -F path=%s -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged\n", $1 }' >> priv.rules
-a always,exit -F arch=b32 -S init_module,finit_module -F key=module-load
-a always,exit -F arch=b64 -S init_module,finit_module -F key=module-load
-a always,exit -F arch=b32 -S delete_module -F key=module-unload
-a always,exit -F arch=b64 -S delete_module -F key=module-unload
-w /bin/kmod -p x -k auoms -k kernelmodules
-w /var/log/audit -p wxa -k audittampering -k auoms
-w /etc/audit -p wxa -k audittampering -k auoms
-w /etc/passwd -p x -k auoms -k usergroup
-w /etc/group -p x -k auoms -k usergroup
-w /etc/pam.d -p wxa -k auoms -k pam
-a always,exit -F arch=b32 -S execve,execveat -F key=auoms
-a always,exit -F arch=b64 -S execve,execveat -F key=auoms
~~~

3. Run `auditctl -l`

Actual results:

The below KASAN use-after-free report is logged in dmesg on boot:

~~~
[  100.574191] ==================================================================
[  100.575760] BUG: KASAN: use-after-free in audit_krule_to_data+0x5b2/0xb70
[  100.577103] Read of size 16 at addr ffff8881053a7360 by task auditctl/1404
[  100.578457] 
[  100.578805] CPU: 1 PID: 1404 Comm: auditctl Tainted: G                 ---------h---  5.14.0-0.rc2.23.el9.x86_64+debug #1
[  100.581040] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016
[  100.583205] Call Trace:
[  100.583747]  dump_stack_lvl+0x57/0x7d
[  100.584527]  print_address_description.constprop.0+0x1f/0x140
[  100.585717]  ? audit_krule_to_data+0x5b2/0xb70
[  100.586648]  __kasan_report.cold+0x7f/0x11e
[  100.587536]  ? audit_krule_to_data+0x5b2/0xb70
[  100.589889]  kasan_report+0x38/0x50
[  100.592035]  kasan_check_range+0xf5/0x1d0
[  100.594270]  memcpy+0x20/0x60
[  100.596285]  audit_krule_to_data+0x5b2/0xb70
[  100.598547]  audit_list_rules_send+0x2d8/0x4c0
[  100.600815]  audit_receive_msg+0xaa3/0x1ae0
[  100.602982]  ? audit_receive+0x7c/0x1b0
[  100.605059]  ? audit_log_feature_change.part.0+0x160/0x160
[  100.607461]  ? __mutex_lock+0xb77/0x1170
[  100.609567]  ? audit_receive+0x7c/0x1b0
[  100.611687]  ? mutex_lock_io_nested+0xfc0/0xfc0
[  100.613933]  ? __lock_release+0x494/0xa40
[  100.616072]  ? rcu_read_unlock+0x40/0x40
[  100.618173]  ? lock_downgrade+0x110/0x110
[  100.620311]  audit_receive+0xd7/0x1b0
[  100.622313]  netlink_unicast+0x430/0x700
[  100.624379]  ? netlink_attachskb+0x750/0x750
[  100.626504]  ? __lock_release+0x494/0xa40
[  100.628588]  netlink_sendmsg+0x72a/0xc70
[  100.630641]  ? netlink_unicast+0x700/0x700
[  100.632727]  ? kmem_cache_alloc_trace+0x1ae/0x330
[  100.634922]  ? netlink_unicast+0x700/0x700
[  100.636971]  sock_sendmsg+0xe4/0x110
[  100.638893]  __sys_sendto+0x1aa/0x280
[  100.640802]  ? __ia32_sys_getpeername+0xb0/0xb0
[  100.642877]  ? find_held_lock+0x33/0x110
[  100.644811]  ? lock_downgrade+0x110/0x110
[  100.646715]  ? rcu_read_unlock+0x40/0x40
[  100.648592]  ? lockdep_hardirqs_on_prepare.part.0+0x19a/0x350
[  100.650782]  ? ktime_get_coarse_real_ts64+0x128/0x160
[  100.652782]  ? trace_hardirqs_on+0x1c/0x160
[  100.654628]  ? ktime_get_coarse_real_ts64+0x128/0x160
[  100.656655]  __x64_sys_sendto+0xdc/0x1b0
[  100.658437]  ? syscall_trace_enter.constprop.0+0x189/0x260
[  100.660538]  do_syscall_64+0x3b/0x90
[  100.662264]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[  100.664295] RIP: 0033:0x7f60d3290d68
[  100.666030] Code: 89 02 48 c7 c0 ff ff ff ff eb b5 0f 1f 80 00 00 00 00 f3 0f 1e fa 8b 05 e6 d6 20 00 41 89 ca 85 c0 75 17 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 78 c3 0f 1f 80 00 00 00 00 41 57 4d 89 c7 41
[  100.673046] RSP: 002b:00007ffff2966c88 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
[  100.673064] RAX: ffffffffffffffda RBX: 0000000000000010 RCX: 00007f60d3290d68
[  100.673069] RDX: 0000000000000010 RSI: 00007ffff2966cc0 RDI: 0000000000000003
[  100.673073] RBP: 0000000000000003 R08: 00007ffff2966cac R09: 000000000000000c
[  100.683739] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffff2966cc0
[  100.686375] R13: 00007ffff2966cac R14: 0000000000000001 R15: 0000000000000000
[  100.689066] 
[  100.690623] Allocated by task 1325:
[  100.692576]  kasan_save_stack+0x1b/0x40
[  100.694601]  __kasan_kmalloc+0x7c/0x90
[  100.696604]  kernfs_fop_open+0x7b3/0xbb0
[  100.698641]  do_dentry_open+0x427/0xec0
[  100.700678]  do_open+0x698/0xec0
[  100.702573]  path_openat+0x27d/0x680
[  100.704530]  do_filp_open+0x1aa/0x3e0
[  100.706512]  do_sys_openat2+0x122/0x370
[  100.708522]  __x64_sys_openat+0x11f/0x1d0
[  100.710570]  do_syscall_64+0x3b/0x90
[  100.712514]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[  100.714759] 
[  100.716310] Last potentially related work creation:
[  100.718534]  kasan_save_stack+0x1b/0x40
[  100.720565]  kasan_record_aux_stack+0xa5/0xb0
[  100.722695]  kvfree_call_rcu+0x79/0x7b0
[  100.724728]  audit_trim_trees+0x434/0x530
[  100.726784]  audit_receive_msg+0xd46/0x1ae0
[  100.728863]  audit_receive+0xd7/0x1b0
[  100.730826]  netlink_unicast+0x430/0x700
[  100.732828]  netlink_sendmsg+0x72a/0xc70
[  100.734815]  sock_sendmsg+0xe4/0x110
[  100.736723]  __sys_sendto+0x1aa/0x280
[  100.738637]  __x64_sys_sendto+0xdc/0x1b0
[  100.740595]  do_syscall_64+0x3b/0x90
[  100.742469]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[  100.744597] 
[  100.745986] The buggy address belongs to the object at ffff8881053a7300
[  100.745986]  which belongs to the cache kmalloc-128 of size 128
[  100.750502] The buggy address is located 96 bytes inside of
[  100.750502]  128-byte region [ffff8881053a7300, ffff8881053a7380)
[  100.754809] The buggy address belongs to the page:
[  100.756804] page:000000004fcb5951 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8881053a7e00 pfn:0x1053a7
[  100.761082] flags: 0x17ffffc0000200(slab|node=0|zone=2|lastcpupid=0x1fffff)
[  100.763579] raw: 0017ffffc0000200 ffffea0000095348 ffffea0000281888 ffff8881000418c0
[  100.766258] raw: ffff8881053a7e00 000000000010000c 00000001ffffffff 0000000000000000
[  100.768955] page dumped because: kasan: bad access detected
[  100.771261] 
[  100.772781] Memory state around the buggy address:
[  100.774959]  ffff8881053a7200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  100.777639]  ffff8881053a7280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  100.780353] >ffff8881053a7300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  100.783073]                                                        ^
[  100.785657]  ffff8881053a7380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  100.788442]  ffff8881053a7400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[  100.791253] ==================================================================
[  100.794073] Disabling lock debugging due to kernel taint
~~~

Expected results:

No use-after-free in audit_krule_to_data

Additional info:
Comment 2 Steve Grubb 2021-07-26 16:16:58 UTC 
Best I can determine is that we are here:
memcpy+0x20/0x60 
audit_krule_to_data+0x5b2/0xb70 
audit_list_rules_send (kernel/auditfilter.c:1092 kernel/auditfilter.c:1181) 
audit_receive_msg (kernel/audit.c:1308) 
? audit_receive (./include/net/netlink.h:631 kernel/audit.c:1542) 
? audit_log_feature_change.part.0 (kernel/audit.c:1018 kernel/audit.c:1196)

audit_krule_to_data offset is not resolving and that is the key piece of information needed. There are 5 different calls to audit_pack_string() which in turn calls memcpy. But determining which of the calls is important since that points to where the memory came from.

Looking at audit_krule_to_data(), there is a memset called for some reason. It does not zero the whole buffer as far as I can tell (0x82/0x110). But it probably should to prevent leaking secrets to user space.
Comment 3 Richard Guy Briggs 2021-08-24 16:14:26 UTC 
2021-08-23 fix posted upstream
https://lkml.org/lkml/2021/8/23/1115
https://listman.redhat.com/archives/linux-audit/2021-August/msg00061.html
Comment 4 Richard Guy Briggs 2021-08-24 16:24:41 UTC 
See https://bugzilla.redhat.com/show_bug.cgi?id=1978123 (dup/clone?)
Comment 8 Veronika Kabatova 2021-10-18 11:16:21 UTC 
(In reply to Linqing Lu from comment #7)

> 
> There is no kernel-debug* packages in CKI MR builds.
> (cc Veronika - any plan/workaround that we can get debug kernel for MR
> builds? Thanks!)
> 
> Will skip pre-verification if that's difficult to come by right now.

Hi,

CKI is planning to add debug kernel builds for x86_64 in Q4. We have to
work around the artifact size limitation GitLab has in place, as debug
builds are larger than this limit. We'll announce on kernel-info and
kernel-qe lists when this functionality is in place.

Until then, please use Brew to build debug kernels when they are needed.
Comment 9 Richard Guy Briggs 2021-10-19 19:33:19 UTC 
Replaced by https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/81
Comment 13 Jarod Wilson 2021-11-05 13:30:22 UTC 
List of commits available on kernel-5.14.0-12.el9 (1/1):
Related commit: f0685cf84480 ("Merge: audit: move put_tree() to avoid trim_trees refcount underflow and UAF")
Related commit: fcab9483ca9e ("audit: move put_tree() to avoid trim_trees refcount underflow and UAF")
Comment 16 Linqing Lu 2021-11-11 03:30:10 UTC 
Initial tests passed on RHEL-9.0.0-20211108.7 but Beaker truncated dmesg so the automated test couldn't fully work yet.
Manually verified for now.
Comment 18 errata-xmlrpc 2022-05-17 15:38:51 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (new packages: kernel), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2022:3907
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