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:

? 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

---[ 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 c...

Classification

CVE ID: CVE-2023-52443

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 5.06% (scored less or equal to compared to others)

EPSS Date: 2025-02-03 (when was this score calculated)

References

https://git.kernel.org/stable/c/9286ee97aa4803d99185768735011d0d65827c9e
https://git.kernel.org/stable/c/1d8e62b5569cc1466ceb8a7e4872cf10160a9dcf
https://git.kernel.org/stable/c/5ff00408e5029d3550ee77f62dc15f1e15c47f87
https://git.kernel.org/stable/c/0a12db736edbb4933e4274932aeea594b5876fa4
https://git.kernel.org/stable/c/9d4fa5fe2b1d56662afd14915a73b4d0783ffa45
https://git.kernel.org/stable/c/5c0392fdafb0a2321311900be83ffa572bef8203
https://git.kernel.org/stable/c/77ab09b92f16c8439a948d1af489196953dc4a0e
https://git.kernel.org/stable/c/55a8210c9e7d21ff2644809699765796d4bfb200

Timeline