Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2024-56755

Disclosure Date: December 29, 2024
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

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

netfs/fscache: Add a memory barrier for FSCACHE_VOLUME_CREATING

In fscache_create_volume(), there is a missing memory barrier between the
bit-clearing operation and the wake-up operation. This may cause a
situation where, after a wake-up, the bit-clearing operation hasn’t been
detected yet, leading to an indefinite wait. The triggering process is as
follows:

[cookie1] [cookie2] [volume_work]
fscache_perform_lookup
fscache_create_volume

                    fscache_perform_lookup
                      fscache_create_volume
		                        fscache_create_volume_work
                                              cachefiles_acquire_volume
                                              clear_and_wake_up_bit
test_and_set_bit
                        test_and_set_bit
                          goto maybe_wait
  goto no_wait

In the above process, cookie1 and cookie2 has the same volume. When cookie1
enters the -no_wait- process, it will clear the bit and wake up the waiting
process. If a barrier is missing, it may cause cookie2 to remain in the
-wait- process indefinitely.

In commit 3288666c7256 (“fscache: Use clear_and_wake_up_bit() in
fscache_create_volume_work()”), barriers were added to similar operations
in fscache_create_volume_work(), but fscache_create_volume() was missed.

By combining the clear and wake operations into clear_and_wake_up_bit() to
fix this issue.

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CVSS V3 Severity and Metrics
Base Score:
5.5 Medium
Impact Score:
3.6
Exploitability Score:
1.8
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
None
Integrity (I):
None
Availability (A):
High

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Technical Analysis