CVE Descriptions

nfc: llcp: Fix memleak in nfc_llcp_send_ui_frame().

In the Linux kernel, the following vulnerability has been resolved: nfc: llcp: Fix memleak in nfc_llcp_send_ui_frame(). syzbot reported various memory leaks related to NFC, struct nfc_llcp_sock, sk_buff, nfc_dev, etc. [0] The leading log hinted that nfc_llcp_send_ui_frame() failed to allocate skb due to sock_error(sk) being -ENXIO. ENXIO is set by nfc_llcp_socket_release() when struct nfc_llcp_local is destroyed by local_cleanup(). The problem is that there is no synchronisation between nfc_llcp_send_ui_frame() and local_cleanup(), and skb could be put into local->tx_queue after it was purged in local_cleanup(): CPU1 CPU2 ---- ---- nfc_llcp_send_ui_frame() local_cleanup() |- do { ' |- pdu = nfc_alloc_send_skb(..., &err) | . | |- nfc_llcp_socket_release(local, false, ENXIO); | |- skb_queue_purge(&local->tx_queue); | | ' | |- skb_queue_tail(&local->tx_queue, pdu); | ... | |- pdu = nfc_alloc_send_skb(..., &err) | ^._________________________________.' local_cleanup() is called for struct nfc_llcp_local only after nfc_llcp_remove_local() unlinks it from llcp_devices. If we hold local->tx_queue.lock then, we can synchronise the thread and nfc_llcp_send_ui_frame(). Let's do that and check list_empty(&local->list) before queuing skb to local->tx_queue in nfc_llcp_send_ui_frame(). [0]: [ 56.074943][ T6096] llcp: nfc_llcp_send_ui_frame: Could not allocate PDU (error=-6) [ 64.318868][ T5813] kmemleak: 6 new suspected memory leaks (see /sys/kernel/debug/kmemleak) BUG: memory leak unreferenced object 0xffff8881272f6800 (size 1024): comm "syz.0.17", pid 6096, jiffies 4294942766 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 27 00 03 40 00 00 00 00 00 00 00 00 00 00 00 00 '..@............ backtrace (crc da58d84d): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4979 [inline] slab_alloc_node mm/slub.c:5284 [inline] __do_kmalloc_node mm/slub.c:5645 [inline] __kmalloc_noprof+0x3e3/0x6b0 mm/slub.c:5658 kmalloc_noprof include/linux/slab.h:961 [inline] sk_prot_alloc+0x11a/0x1b0 net/core/sock.c:2239 sk_alloc+0x36/0x360 net/core/sock.c:2295 nfc_llcp_sock_alloc+0x37/0x130 net/nfc/llcp_sock.c:979 llcp_sock_create+0x71/0xd0 net/nfc/llcp_sock.c:1044 nfc_sock_create+0xc9/0xf0 net/nfc/af_nfc.c:31 __sock_create+0x1a9/0x340 net/socket.c:1605 sock_create net/socket.c:1663 [inline] __sys_socket_create net/socket.c:1700 [inline] __sys_socket+0xb9/0x1a0 net/socket.c:1747 __do_sys_socket net/socket.c:1761 [inline] __se_sys_socket net/socket.c:1759 [inline] __x64_sys_socket+0x1b/0x30 net/socket.c:1759 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa4/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f BUG: memory leak unreferenced object 0xffff88810fbd9800 (size 240): comm "syz.0.17", pid 6096, jiffies 4294942850 hex dump (first 32 bytes): 68 f0 ff 08 81 88 ff ff 68 f0 ff 08 81 88 ff ff h.......h....... 00 00 00 00 00 00 00 00 00 68 2f 27 81 88 ff ff .........h/'.... backtrace (crc 6cc652b1): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4979 [inline] slab_alloc_node mm/slub.c:5284 [inline] kmem_cache_alloc_node_noprof+0x36f/0x5e0 mm/slub.c:5336 __alloc_skb+0x203/0x240 net/core/skbuff.c:660 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_skb_with_frags+0x69/0x3f0 net/core/sk ---truncated---

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-401	Missing Release of Memory after Effective Lifetime The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.1	5.5	MEDIUM	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H More informations Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Local The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Attack Complexity This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Low Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. Low The attacker requires privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources. User Interaction This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. None The vulnerable system can be exploited without interaction from any user. Base: Scope Metrics The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Scope Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. Unchanged An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. None There is no loss of confidentiality within the impacted component. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. None There is no loss of integrity within the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. High There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal Metrics The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability. Environmental Metrics These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.	nvd@nist.gov

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

EPSS First.org