In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix UAF in decryption with multichannel
After commit f7025d861694 ("smb: client: allocate crypto only for
primary server") and commit b0abcd65ec54 ("smb: client: fix UAF in
async decryption"), the channels started reusing AEAD TFM from primary
channel to perform synchronous decryption, but that can't done as
there could be multiple cifsd threads (one per channel) simultaneously
accessing it to perform decryption.
This fixes the following KASAN splat when running fstest generic/249
with 'vers=3.1.1,multichannel,max_channels=4,seal' against Windows
Server 2022:
BUG: KASAN: slab-use-after-free in gf128mul_4k_lle+0xba/0x110
Read of size 8 at addr ffff8881046c18a0 by task cifsd/986
CPU: 3 UID: 0 PID: 986 Comm: cifsd Not tainted 6.15.0-rc1 #1
PREEMPT(voluntary)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-3.fc41
04/01/2014
Call Trace:
dump_stack_lvl+0x5d/0x80
print_report+0x156/0x528
? gf128mul_4k_lle+0xba/0x110
? __virt_addr_valid+0x145/0x300
? __phys_addr+0x46/0x90
? gf128mul_4k_lle+0xba/0x110
kasan_report+0xdf/0x1a0
? gf128mul_4k_lle+0xba/0x110
gf128mul_4k_lle+0xba/0x110
ghash_update+0x189/0x210
shash_ahash_update+0x295/0x370
? __pfx_shash_ahash_update+0x10/0x10
? __pfx_shash_ahash_update+0x10/0x10
? __pfx_extract_iter_to_sg+0x10/0x10
? ___kmalloc_large_node+0x10e/0x180
? __asan_memset+0x23/0x50
crypto_ahash_update+0x3c/0xc0
gcm_hash_assoc_remain_continue+0x93/0xc0
crypt_message+0xe09/0xec0 [cifs]
? __pfx_crypt_message+0x10/0x10 [cifs]
? _raw_spin_unlock+0x23/0x40
? __pfx_cifs_readv_from_socket+0x10/0x10 [cifs]
decrypt_raw_data+0x229/0x380 [cifs]
? __pfx_decrypt_raw_data+0x10/0x10 [cifs]
? __pfx_cifs_read_iter_from_socket+0x10/0x10 [cifs]
smb3_receive_transform+0x837/0xc80 [cifs]
? __pfx_smb3_receive_transform+0x10/0x10 [cifs]
? __pfx___might_resched+0x10/0x10
? __pfx_smb3_is_transform_hdr+0x10/0x10 [cifs]
cifs_demultiplex_thread+0x692/0x1570 [cifs]
? __pfx_cifs_demultiplex_thread+0x10/0x10 [cifs]
? rcu_is_watching+0x20/0x50
? rcu_lockdep_current_cpu_online+0x62/0xb0
? find_held_lock+0x32/0x90
? kvm_sched_clock_read+0x11/0x20
? local_clock_noinstr+0xd/0xd0
? trace_irq_enable.constprop.0+0xa8/0xe0
? __pfx_cifs_demultiplex_thread+0x10/0x10 [cifs]
kthread+0x1fe/0x380
? kthread+0x10f/0x380
? __pfx_kthread+0x10/0x10
? local_clock_noinstr+0xd/0xd0
? ret_from_fork+0x1b/0x60
? local_clock+0x15/0x30
? lock_release+0x29b/0x390
? rcu_is_watching+0x20/0x50
? __pfx_kthread+0x10/0x10
ret_from_fork+0x31/0x60
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.5% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it