linux-stable.git/kernel/audit.c, branch linux-rolling-lts

audit: fix potential integer overflow in audit_log_n_hex()

2026-07-18T14:53:30+00:00

commit 65dfde57d1e29ce2b76fc23dd565eccd5c0bc0f0 upstream.

The function calculates new_len as len << 1 for hex encoding. This
has two overflow risks: the shift itself can overflow when len is
large, and the result can be truncated when assigned to new_len
(declared as int) from the size_t calculation.

Fix by using check_shl_overflow() to catch shift overflow and
changing new_len and loop counter i to size_t to prevent truncation.

Cc: stable@vger.kernel.org
Fixes: 168b7173959f ("AUDIT: Clean up logging of untrusted strings")
Reviewed-by: Richard Guy Briggs 
Signed-off-by: Ricardo Robaina 
[PM: remove vertical whitspace noise]
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

audit: Fix data races of skb_queue_len() readers on audit_queue

2026-07-18T14:53:15+00:00

commit c9a71daaecb2fb1d8c704545cc0b1c920b9bf5d7 upstream.

Multiple readers access audit_queue.qlen via skb_queue_len() without
holding the queue lock or using READ_ONCE(), while kauditd writes to
this field via the skb_dequeue() → __skb_unlink() path with WRITE_ONCE()
protected by a spinlock. This constitutes data races.

All affected skb_queue_len(&audit_queue) call sites:
  - kauditd_thread() wait_event_freezable() condition
  - audit_receive_msg() AUDIT_GET handler (s.backlog assignment)
  - audit_receive() backlog check
  - audit_log_start() backlog check and pr_warn()

KCSAN reports the following conflicting access pattern (one example):
==================================================================
BUG: KCSAN: data-race in audit_log_start / skb_dequeue

write (marked) to 0xffffffff8512ee20 of 4 bytes by task 661 on cpu 57:
 skb_dequeue+0x70/0xf0
 kauditd_send_queue+0x71/0x220
 kauditd_thread+0x1cb/0x430
 kthread+0x1c2/0x210
 ret_from_fork+0x162/0x1a0
 ret_from_fork_asm+0x1a/0x30

read to 0xffffffff8512ee20 of 4 bytes by task 36586 on cpu 1:
 audit_log_start+0x2a0/0x6b0
 audit_core_dumps+0x64/0xa0
 do_coredump+0x14b/0x1260
 get_signal+0xeb2/0xf70
 arch_do_signal_or_restart+0x41/0x170
 exit_to_user_mode_loop+0xa2/0x1c0
 do_syscall_64+0x1a3/0x1c0
 entry_SYSCALL_64_after_hwframe+0x76/0xe0

value changed: 0x00000001 -> 0x00000000
==================================================================

Resolve the race by switching to lockless helper skb_queue_len_lockless(),
which internally uses READ_ONCE() and properly pairs with the WRITE_ONCE()
write accesses already present on the writer side.

Cc: stable@vger.kernel.org
Fixes: 3197542482df ("audit: rework audit_log_start()")
Signed-off-by: Chi Wang 
Reviewed-by: Ricardo Robaina 
[PM: line length tweak]
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

audit: enforce AUDIT_LOCKED for AUDIT_TRIM and AUDIT_MAKE_EQUIV

2026-05-23T11:07:16+00:00

commit f9e1c1324b4d98d591a6f7568fdebf5cf456dfc2 upstream.

AUDIT_ADD_RULE and AUDIT_DEL_RULE correctly check for AUDIT_LOCKED
and return -EPERM, but AUDIT_TRIM and AUDIT_MAKE_EQUIV do not. This
allows a process with CAP_AUDIT_CONTROL to modify directory tree
watches and equivalence mappings even when the audit configuration
has been locked, undermining the purpose of the lock.

Add AUDIT_LOCKED checks to both commands.

Cc: stable@vger.kernel.org
Reviewed-by: Ricardo Robaina 
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Sergio Correia 
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

audit: fix skb leak when audit rate limit is exceeded

2025-09-10T23:55:00+00:00

When configuring a small audit rate limit in
/etc/audit/rules.d/audit.rules:
-a always,exit -F arch=b64 -S openat -S truncate -S ftruncate
-F exit=-EACCES -F auid>=1000 -F auid!=4294967295 -k access -r 100

And then repeatedly triggering permission denied as a normal user:
while :; do cat /proc/1/environ; done

We can see the messages in kernel log:
  [ 2531.862184] audit: rate limit exceeded

The unreclaimable slab objects start to leak quickly. With kmemleak
enabled, many call traces appear like:
unreferenced object 0xffff99144b13f600 (size 232):
  comm "cat", pid 1100, jiffies 4294739144
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 8540ec4f):
    kmemleak_alloc+0x4a/0x90
    kmem_cache_alloc_node+0x2ea/0x390
    __alloc_skb+0x174/0x1b0
    audit_log_start+0x198/0x3d0
    audit_log_proctitle+0x32/0x160
    audit_log_exit+0x6c6/0x780
    __audit_syscall_exit+0xee/0x140
    syscall_exit_work+0x12b/0x150
    syscall_exit_to_user_mode_prepare+0x39/0x80
    syscall_exit_to_user_mode+0x11/0x260
    do_syscall_64+0x8c/0x180
    entry_SYSCALL_64_after_hwframe+0x78/0x80

This shows that the skb allocated in audit_log_start() and queued
onto skb_list is never freed.

In audit_log_end(), each skb is dequeued from skb_list and passed
to __audit_log_end(). However, when the audit rate limit is exceeded,
__audit_log_end() simply prints "rate limit exceeded" and returns
without processing the skb. Since the skb is already removed from
skb_list, audit_buffer_free() cannot free it later, leading to a
memory leak.

Fix this by freeing the skb when the rate limit is exceeded.

Fixes: eb59d494eebd ("audit: add record for multiple task security contexts")
Signed-off-by: Gerald Yang 
[PM: fixes tag, subj tweak]
Signed-off-by: Paul Moore

audit: init ab->skb_list earlier in audit_buffer_alloc()

2025-09-04T15:06:33+00:00

syzbot found a bug in audit_buffer_alloc() if nlmsg_new() returns NULL.

We need to initialize ab->skb_list before calling audit_buffer_free()
which will use both the skb_list spinlock and list pointers.

Fixes: eb59d494eebd ("audit: add record for multiple task security contexts")
Reported-by: syzbot+bb185b018a51f8d91fd2@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/68b93e3c.a00a0220.eb3d.0000.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet 
Cc: Casey Schaufler 
Cc: Paul Moore 
Cc: Eric Paris 
Cc: audit@vger.kernel.org
Signed-off-by: Paul Moore

audit: add record for multiple object contexts

2025-08-30T14:15:30+00:00

Create a new audit record AUDIT_MAC_OBJ_CONTEXTS.
An example of the MAC_OBJ_CONTEXTS record is:

    type=MAC_OBJ_CONTEXTS
      msg=audit(1601152467.009:1050):
      obj_selinux=unconfined_u:object_r:user_home_t:s0

When an audit event includes a AUDIT_MAC_OBJ_CONTEXTS record
the "obj=" field in other records in the event will be "obj=?".
An AUDIT_MAC_OBJ_CONTEXTS record is supplied when the system has
multiple security modules that may make access decisions based
on an object security context.

Signed-off-by: Casey Schaufler 
[PM: subj tweak, audit example readability indents]
Signed-off-by: Paul Moore

audit: add record for multiple task security contexts

2025-08-30T14:15:30+00:00

Replace the single skb pointer in an audit_buffer with a list of
skb pointers. Add the audit_stamp information to the audit_buffer as
there's no guarantee that there will be an audit_context containing
the stamp associated with the event. At audit_log_end() time create
auxiliary records as have been added to the list. Functions are
created to manage the skb list in the audit_buffer.

Create a new audit record AUDIT_MAC_TASK_CONTEXTS.
An example of the MAC_TASK_CONTEXTS record is:

    type=MAC_TASK_CONTEXTS
      msg=audit(1600880931.832:113)
      subj_apparmor=unconfined
      subj_smack=_

When an audit event includes a AUDIT_MAC_TASK_CONTEXTS record the
"subj=" field in other records in the event will be "subj=?".
An AUDIT_MAC_TASK_CONTEXTS record is supplied when the system has
multiple security modules that may make access decisions based on a
subject security context.

Refactor audit_log_task_context(), creating a new audit_log_subj_ctx().
This is used in netlabel auditing to provide multiple subject security
contexts as necessary.

Suggested-by: Paul Moore 
Signed-off-by: Casey Schaufler 
[PM: subj tweak, audit example readability indents]
Signed-off-by: Paul Moore

lsm: security_lsmblob_to_secctx module selection

2025-08-30T14:15:29+00:00

Add a parameter lsmid to security_lsmblob_to_secctx() to identify which
of the security modules that may be active should provide the security
context. If the value of lsmid is LSM_ID_UNDEF the first LSM providing
a hook is used. security_secid_to_secctx() is unchanged, and will
always report the first LSM providing a hook.

Signed-off-by: Casey Schaufler 
[PM: subj tweak]
Signed-off-by: Paul Moore

audit: create audit_stamp structure

2025-08-30T14:15:28+00:00

Replace the timestamp and serial number pair used in audit records
with a structure containing the two elements.

Signed-off-by: Casey Schaufler 
[PM: subj tweak]
Signed-off-by: Paul Moore

audit: record AUDIT_ANOM_* events regardless of presence of rules

2025-04-11T18:14:41+00:00

When no audit rules are in place, AUDIT_ANOM_{LINK,CREAT} events
reported in audit_log_path_denied() are unconditionally dropped due to
an explicit check for the existence of any audit rules.  Given this is a
report of a security violation, allow it to be recorded regardless of
the existence of any audit rules.

To test,
	mkdir -p /root/tmp
	chmod 1777 /root/tmp
	touch /root/tmp/test.txt
	useradd test
	chown test /root/tmp/test.txt
	{echo C0644 12 test.txt; printf 'hello\ntest1\n'; printf \\000;} | \
		scp -t /root/tmp
Check with
	ausearch -m ANOM_CREAT -ts recent

Link: https://issues.redhat.com/browse/RHEL-9065
Signed-off-by: Richard Guy Briggs 
Signed-off-by: Paul Moore