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CVE-2024-35970— af_unix: Clear stale u->oob_skb.

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于存在死锁。

AI Predicted 4.3 Difficulty: Moderate EPSS 0.50% · P42

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux 314001f0bf927015e459c9d387d62a231fe93af3< b4bc99d04c689b5652665394ae8d3e02fb754153 affected
314001f0bf927015e459c9d387d62a231fe93af3< 84a352b7eba1142a95441380058985ff19f25ec9 affected
314001f0bf927015e459c9d387d62a231fe93af3< 601a89ea24d05089debfa2dc896ea9f5937ac7a6 affected
314001f0bf927015e459c9d387d62a231fe93af3< 698a95ade1a00e6494482046902b986dfffd1caf affected
314001f0bf927015e459c9d387d62a231fe93af3< b46f4eaa4f0ec38909fb0072eea3aeddb32f954e affected
5.15 affected
< 5.15 unaffected
5.15.156≤ 5.15.* unaffected
… +4 more rows
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I. Basic Information for CVE-2024-35970

Vulnerability Information
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Vulnerability Title
af_unix: Clear stale u->oob_skb.
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: af_unix: Clear stale u->oob_skb. syzkaller started to report deadlock of unix_gc_lock after commit 4090fa373f0e ("af_unix: Replace garbage collection algorithm."), but it just uncovers the bug that has been there since commit 314001f0bf92 ("af_unix: Add OOB support"). The repro basically does the following. from socket import * from array import array c1, c2 = socketpair(AF_UNIX, SOCK_STREAM) c1.sendmsg([b'a'], [(SOL_SOCKET, SCM_RIGHTS, array("i", [c2.fileno()]))], MSG_OOB) c2.recv(1) # blocked as no normal data in recv queue c2.close() # done async and unblock recv() c1.close() # done async and trigger GC A socket sends its file descriptor to itself as OOB data and tries to receive normal data, but finally recv() fails due to async close(). The problem here is wrong handling of OOB skb in manage_oob(). When recvmsg() is called without MSG_OOB, manage_oob() is called to check if the peeked skb is OOB skb. In such a case, manage_oob() pops it out of the receive queue but does not clear unix_sock(sk)->oob_skb. This is wrong in terms of uAPI. Let's say we send "hello" with MSG_OOB, and "world" without MSG_OOB. The 'o' is handled as OOB data. When recv() is called twice without MSG_OOB, the OOB data should be lost. >>> from socket import * >>> c1, c2 = socketpair(AF_UNIX, SOCK_STREAM, 0) >>> c1.send(b'hello', MSG_OOB) # 'o' is OOB data 5 >>> c1.send(b'world') 5 >>> c2.recv(5) # OOB data is not received b'hell' >>> c2.recv(5) # OOB date is skipped b'world' >>> c2.recv(5, MSG_OOB) # This should return an error b'o' In the same situation, TCP actually returns -EINVAL for the last recv(). Also, if we do not clear unix_sk(sk)->oob_skb, unix_poll() always set EPOLLPRI even though the data has passed through by previous recv(). To avoid these issues, we must clear unix_sk(sk)->oob_skb when dequeuing it from recv queue. The reason why the old GC did not trigger the deadlock is because the old GC relied on the receive queue to detect the loop. When it is triggered, the socket with OOB data is marked as GC candidate because file refcount == inflight count (1). However, after traversing all inflight sockets, the socket still has a positive inflight count (1), thus the socket is excluded from candidates. Then, the old GC lose the chance to garbage-collect the socket. With the old GC, the repro continues to create true garbage that will never be freed nor detected by kmemleak as it's linked to the global inflight list. That's why we couldn't even notice the issue.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于存在死锁。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 314001f0bf927015e459c9d387d62a231fe93af3 ~ b4bc99d04c689b5652665394ae8d3e02fb754153 -
Linux Linux 5.15 -

II. Public POCs for CVE-2024-35970

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III. Intelligence Information for CVE-2024-35970

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Other References for CVE-2024-35970 (5)

Same Patch Batch · Linux · 2024-05-20 · 62 CVEs total

CVE-2024-35969 8.8 HIGH ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr
CVE-2024-35980 8.4 HIGH arm64: tlb: Fix TLBI RANGE operand
CVE-2024-35987 8.4 HIGH riscv: Fix loading 64-bit NOMMU kernels past the start of RAM
CVE-2024-35993 7.8 HIGH mm: turn folio_test_hugetlb into a PageType
CVE-2024-36007 7.8 HIGH mlxsw: spectrum_acl_tcam: Fix warning during rehash
CVE-2024-36001 7.8 HIGH netfs: Fix the pre-flush when appending to a file in writethrough mode
CVE-2024-35954 7.8 HIGH scsi: sg: Avoid sg device teardown race
CVE-2024-35949 7.8 HIGH btrfs: make sure that WRITTEN is set on all metadata blocks
CVE-2024-35950 7.8 HIGH drm/client: Fully protect modes[] with dev->mode_config.mutex
CVE-2024-35951 7.8 HIGH drm/panfrost: Fix the error path in panfrost_mmu_map_fault_addr()
CVE-2024-35948 7.8 HIGH bcachefs: Check for journal entries overruning end of sb clean section
CVE-2024-35994 7.8 HIGH firmware: qcom: uefisecapp: Fix memory related IO errors and crashes
CVE-2024-35990 7.8 HIGH dma: xilinx_dpdma: Fix locking
CVE-2024-35958 7.8 HIGH net: ena: Fix incorrect descriptor free behavior
CVE-2024-36009 7.8 HIGH ax25: Fix netdev refcount issue
CVE-2024-35979 7.8 HIGH raid1: fix use-after-free for original bio in raid1_write_request()
CVE-2024-35968 7.8 HIGH pds_core: Fix pdsc_check_pci_health function to use work thread
CVE-2024-35998 7.5 HIGH smb3: fix lock ordering potential deadlock in cifs_sync_mid_result
CVE-2024-35999 7.5 HIGH smb3: missing lock when picking channel
CVE-2024-35971 7.5 HIGH net: ks8851: Handle softirqs at the end of IRQ thread to fix hang

Showing top 20 of 62 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2024-35970

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