NULL Pointer Dereference Affecting kernel-default package, versions <5.14.21-150400.24.111.2
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applicationsSnyk Learn
Learn about NULL Pointer Dereference vulnerabilities in an interactive lesson.
Start learning- Snyk IDSNYK-SLES154-KERNELDEFAULT-6445256
- published15 Mar 2024
- disclosed14 Mar 2024
Introduced: 14 Mar 2024
CVE-2023-52443 (opens in a new tab)How to fix?
Upgrade SLES:15.4 kernel-default to version 5.14.21-150400.24.111.2 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-default package and not the kernel-default package as distributed by SLES.
See How to fix? for SLES:15.4 relevant fixed versions and status.
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).
References
- https://www.suse.com/security/cve/CVE-2023-52443.html
- https://bugzilla.suse.com/1220240
- https://git.kernel.org/stable/c/0a12db736edbb4933e4274932aeea594b5876fa4
- https://git.kernel.org/stable/c/1d8e62b5569cc1466ceb8a7e4872cf10160a9dcf
- https://git.kernel.org/stable/c/55a8210c9e7d21ff2644809699765796d4bfb200
- https://git.kernel.org/stable/c/5c0392fdafb0a2321311900be83ffa572bef8203
- https://git.kernel.org/stable/c/5ff00408e5029d3550ee77f62dc15f1e15c47f87
- https://git.kernel.org/stable/c/77ab09b92f16c8439a948d1af489196953dc4a0e
- https://git.kernel.org/stable/c/9286ee97aa4803d99185768735011d0d65827c9e
- https://git.kernel.org/stable/c/9d4fa5fe2b1d56662afd14915a73b4d0783ffa45
- https://lists.debian.org/debian-lts-announce/2024/06/msg00016.html
- https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html