On 5/7/24 09:12, Leesoo Ahn wrote:
profile->parent->dents[AAFS_PROF_DIR] could be NULL only if its parent is made
from __create_missing_ancestors(..) and 'ent->old' is NULL in
aa_replace_profiles(..).
In that case, it must return an error code and the code, -ENOENT represents
its state that the path of its parent is not existed yet.

BUG: kernel NULL pointer dereference, address: 0000000000000030
PGD 0 P4D 0
PREEMPT SMP PTI
CPU: 4 PID: 3362 Comm: apparmor_parser Not tainted 6.8.0-24-generic #24
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
RIP: 0010:aafs_create.constprop.0+0x7f/0x130
Code: 4c 63 e0 48 83 c4 18 4c 89 e0 5b 41 5c 41 5d 41 5e 41 5f 5d 31 d2 31 c9 31 f6 
31 ff 45 31 c0 45 31 c9 45 31 d2 c3 cc cc cc cc <4d> 8b 55 30 4d 8d ba a0 00 00 
00 4c 89 55 c0 4c 89 ff e8 7a 6a ae
RSP: 0018:ffffc9000b2c7c98 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00000000000041ed RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000b2c7cd8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82baac10
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007be9f22cf740(0000) GS:ffff88817bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000030 CR3: 0000000134b08000 CR4: 00000000000006f0
Call Trace:
  <TASK>
  ? show_regs+0x6d/0x80
  ? __die+0x24/0x80
  ? page_fault_oops+0x99/0x1b0
  ? kernelmode_fixup_or_oops+0xb2/0x140
  ? __bad_area_nosemaphore+0x1a5/0x2c0
  ? find_vma+0x34/0x60
  ? bad_area_nosemaphore+0x16/0x30
  ? do_user_addr_fault+0x2a2/0x6b0
  ? exc_page_fault+0x83/0x1b0
  ? asm_exc_page_fault+0x27/0x30
  ? aafs_create.constprop.0+0x7f/0x130
  ? aafs_create.constprop.0+0x51/0x130
  __aafs_profile_mkdir+0x3d6/0x480
  aa_replace_profiles+0x83f/0x1270
  policy_update+0xe3/0x180
  profile_load+0xbc/0x150
  ? rw_verify_area+0x47/0x140
  vfs_write+0x100/0x480
  ? __x64_sys_openat+0x55/0xa0
  ? syscall_exit_to_user_mode+0x86/0x260
  ksys_write+0x73/0x100
  __x64_sys_write+0x19/0x30
  x64_sys_call+0x7e/0x25c0
  do_syscall_64+0x7f/0x180
  entry_SYSCALL_64_after_hwframe+0x78/0x80
RIP: 0033:0x7be9f211c574
Code: c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 
80 3d d5 ea 0e 00 00 74 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 
1f 00 55 48 89 e5 48 83 ec 20 48 89
RSP: 002b:00007ffd26f2b8c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00005d504415e200 RCX: 00007be9f211c574
RDX: 0000000000001fc1 RSI: 00005d504418bc80 RDI: 0000000000000004
RBP: 0000000000001fc1 R08: 0000000000001fc1 R09: 0000000080000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00005d504418bc80
R13: 0000000000000004 R14: 00007ffd26f2b9b0 R15: 00007ffd26f2ba30
  </TASK>
Modules linked in: snd_seq_dummy snd_hrtimer qrtr snd_hda_codec_generic 
snd_hda_intel snd_intel_dspcfg snd_intel_sdw_acpi snd_hda_codec snd_hda_core 
snd_hwdep snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq 
snd_seq_device i2c_i801 snd_timer i2c_smbus qxl snd soundcore drm_ttm_helper 
lpc_ich ttm joydev input_leds serio_raw mac_hid binfmt_misc msr parport_pc 
ppdev lp parport efi_pstore nfnetlink dmi_sysfs qemu_fw_cfg ip_tables x_tables 
autofs4 hid_generic usbhid hid ahci libahci psmouse virtio_rng xhci_pci 
xhci_pci_renesas
CR2: 0000000000000030
---[ end trace 0000000000000000 ]---
RIP: 0010:aafs_create.constprop.0+0x7f/0x130
Code: 4c 63 e0 48 83 c4 18 4c 89 e0 5b 41 5c 41 5d 41 5e 41 5f 5d 31 d2 31 c9 31 f6 
31 ff 45 31 c0 45 31 c9 45 31 d2 c3 cc cc cc cc <4d> 8b 55 30 4d 8d ba a0 00 00 
00 4c 89 55 c0 4c 89 ff e8 7a 6a ae
RSP: 0018:ffffc9000b2c7c98 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00000000000041ed RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000b2c7cd8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82baac10
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007be9f22cf740(0000) GS:ffff88817bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000030 CR3: 0000000134b08000 CR4: 00000000000006f0

Signed-off-by: Leesoo Ahn <ls...@ooseel.net>

Acked-by: John Johansen <john.johan...@canonical.com>

I have pulled this into my tree

---
  security/apparmor/apparmorfs.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index bcfea073e3f2..01b923d97a44 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -1692,6 +1692,10 @@ int __aafs_profile_mkdir(struct aa_profile *profile, 
struct dentry *parent)
                struct aa_profile *p;
                p = aa_deref_parent(profile);
                dent = prof_dir(p);
+               if (!dent) {
+                       error = -ENOENT;
+                       goto fail2;
+               }
                /* adding to parent that previously didn't have children */
                dent = aafs_create_dir("profiles", dent);
                if (IS_ERR(dent))


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