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Fencer Vulns
medium 5.5

CVE-2023-52443 json

apparmor: avoid crash when parsed profile name is empty

published 2024-02-22 2 y ago modified 2026-06-17 4 mo ago also EUVD-2023-57068

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

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

apparmor: avoid crash when parsed profile name is empty

When processing a packed profile in unpack_profile() described like

"profile :ns::samba-dcerpcd /usr/lib*/samba/{,samba/}samba-dcerpcd {...}"

a string ":samba-dcerpcd" is unpacked as a fully-qualified name and then passed to aa_splitn_fqname().

aa_splitn_fqname() treats ":samba-dcerpcd" as only containing a namespace. Thus it returns NULL for tmpname, meanwhile tmpns is non-NULL. Later aa_alloc_profile() crashes as the new profile name is NULL now.

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 6 PID: 1657 Comm: apparmor_parser Not tainted 6.7.0-rc2-dirty #16 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014 RIP: 0010:strlen+0x1e/0xa0 Call Trace: <TASK> ? strlen+0x1e/0xa0 aa_policy_init+0x1bb/0x230 aa_alloc_profile+0xb1/0x480 unpack_profile+0x3bc/0x4960 aa_unpack+0x309/0x15e0 aa_replace_profiles+0x213/0x33c0 policy_update+0x261/0x370 profile_replace+0x20e/0x2a0 vfs_write+0x2af/0xe00 ksys_write+0x126/0x250 do_syscall_64+0x46/0xf0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 </TASK> ---[ end trace 0000000000000000 ]--- RIP: 0010:strlen+0x1e/0xa0

It seems such behaviour of aa_splitn_fqname() is expected and checked in other places where it is called (e.g. aa_remove_profiles). Well, there is an explicit comment "a ns name without a following profile is allowed" inside.

AFAICS, nothing can prevent unpacked "name" to be in form like ":samba-dcerpcd" - it is passed from userspace.

Deny the whole profile set replacement in such case and inform user with EPROTO and an explaining message.

Found by Linux Verification Center (linuxtesting.org).

Patch / fix

  • Linux Linux 4.19.306, 5.4.268, 5.10.209, 5.15.148, 6.1.75, 6.6.14, 6.7.2, 6.8
  • linux Debian 12 6.1.76-1
  • linux Debian 14, Debian 13 6.6.15-1

debian advisories DEBIAN-CVE-2023-52443

  • linux Ubuntu 20.04 LTS 5.4.0-176.196
  • linux Ubuntu 22.04 LTS 5.15.0-102.112
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1122.132
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1057.63
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1126.135
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1055.63
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1054.59
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1069.74

ubuntu advisories UBUNTU-CVE-2023-52443

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-rt SLE Micro 5.4, SLE Micro 5.3, openSUSE Leap Micro 5.4 +1 more 5.14.21-150400.15.71.1
  • kernel-source-rt SLE Micro 5.4, SLE Micro 5.3 5.14.21-150400.15.71.1
  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.171.1
  • kernel-syms-rt SLE Real Time 12 SP5 4.12.14-10.171.1
  • kernel-rt_debug SLE Real Time 12 SP5 4.12.14-10.171.1
  • kernel-source-rt SLE Real Time 12 SP5 4.12.14-10.171.1
  • kernel-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.173.1
  • kernel-syms-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.173.1

suse advisories SUSE-SU-2024:0977-1SUSE-SU-2024:0976-1SUSE-SU-2024:0975-1SUSE-SU-2024:0926-1SUSE-SU-2024:0925-1SUSE-SU-2024:0910-1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.