CVE-2023-52443

MEDIUM
Published Feb 22, 2024 Modified Nov 21, 2024 CWE-476

Description

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).

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CVSS v3.1 Score

5.5
MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

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://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

Frequently Asked Questions

What is CVE-2023-52443? +
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). It has a CVSS v3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2023-52443? +
CVE-2023-52443 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2023-52443? +
CVE-2023-52443 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2023-52443? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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