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CVE-2024-26960— mm: swap: fix race between free_swap_and_cache() and swapoff()

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free_swap_and_cache函数和swapoff函数之间存在竞争。

CVSS 7.0 · High EPSS 0.18% · P7

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 7c00bafee87c7bac7ed9eced7c161f8e5332cb4e< d85c11c97ecf92d47a4b29e3faca714dc1f18d0d affected
7c00bafee87c7bac7ed9eced7c161f8e5332cb4e< 2da5568ee222ce0541bfe446a07998f92ed1643e affected
7c00bafee87c7bac7ed9eced7c161f8e5332cb4e< 1ede7f1d7eed1738d1b9333fd1e152ccb450b86a affected
7c00bafee87c7bac7ed9eced7c161f8e5332cb4e< 0f98f6d2fb5fad00f8299b84b85b6bc1b6d7d19a affected
7c00bafee87c7bac7ed9eced7c161f8e5332cb4e< 3ce4c4c653e4e478ecb15d3c88e690f12cbf6b39 affected
7c00bafee87c7bac7ed9eced7c161f8e5332cb4e< 363d17e7f7907c8e27a9e86968af0eaa2301787b affected
7c00bafee87c7bac7ed9eced7c161f8e5332cb4e< 82b1c07a0af603e3c47b906c8e991dc96f01688e affected
4.11 affected
… +8 more rows
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I. Basic Information for CVE-2024-26960

Vulnerability Information
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Vulnerability Title
mm: swap: fix race between free_swap_and_cache() and swapoff()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: mm: swap: fix race between free_swap_and_cache() and swapoff() There was previously a theoretical window where swapoff() could run and teardown a swap_info_struct while a call to free_swap_and_cache() was running in another thread. This could cause, amongst other bad possibilities, swap_page_trans_huge_swapped() (called by free_swap_and_cache()) to access the freed memory for swap_map. This is a theoretical problem and I haven't been able to provoke it from a test case. But there has been agreement based on code review that this is possible (see link below). Fix it by using get_swap_device()/put_swap_device(), which will stall swapoff(). There was an extra check in _swap_info_get() to confirm that the swap entry was not free. This isn't present in get_swap_device() because it doesn't make sense in general due to the race between getting the reference and swapoff. So I've added an equivalent check directly in free_swap_and_cache(). Details of how to provoke one possible issue (thanks to David Hildenbrand for deriving this): --8<----- __swap_entry_free() might be the last user and result in "count == SWAP_HAS_CACHE". swapoff->try_to_unuse() will stop as soon as soon as si->inuse_pages==0. So the question is: could someone reclaim the folio and turn si->inuse_pages==0, before we completed swap_page_trans_huge_swapped(). Imagine the following: 2 MiB folio in the swapcache. Only 2 subpages are still references by swap entries. Process 1 still references subpage 0 via swap entry. Process 2 still references subpage 1 via swap entry. Process 1 quits. Calls free_swap_and_cache(). -> count == SWAP_HAS_CACHE [then, preempted in the hypervisor etc.] Process 2 quits. Calls free_swap_and_cache(). -> count == SWAP_HAS_CACHE Process 2 goes ahead, passes swap_page_trans_huge_swapped(), and calls __try_to_reclaim_swap(). __try_to_reclaim_swap()->folio_free_swap()->delete_from_swap_cache()-> put_swap_folio()->free_swap_slot()->swapcache_free_entries()-> swap_entry_free()->swap_range_free()-> ... WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries); What stops swapoff to succeed after process 2 reclaimed the swap cache but before process1 finished its call to swap_page_trans_huge_swapped()? --8<-----
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
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free_swap_and_cache函数和swapoff函数之间存在竞争。
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 7c00bafee87c7bac7ed9eced7c161f8e5332cb4e ~ d85c11c97ecf92d47a4b29e3faca714dc1f18d0d -
Linux Linux 4.11 -

II. Public POCs for CVE-2024-26960

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III. Intelligence Information for CVE-2024-26960

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Mailing List Discussions for CVE-2024-26960 (1)

Other References for CVE-2024-26960 (7)

Same Patch Batch · Linux · 2024-05-01 · 159 CVEs total

CVE-2024-27388 9.8 CRITICAL SUNRPC: fix some memleaks in gssx_dec_option_array
CVE-2024-26953 9.8 CRITICAL net: esp: fix bad handling of pages from page_pool
CVE-2024-26931 8.8 HIGH scsi: qla2xxx: Fix command flush on cable pull
CVE-2024-27053 8.8 HIGH wifi: wilc1000: fix RCU usage in connect path
CVE-2024-26990 8.8 HIGH KVM: x86/mmu: Write-protect L2 SPTEs in TDP MMU when clearing dirty status
CVE-2024-26952 8.3 HIGH ksmbd: fix potencial out-of-bounds when buffer offset is invalid
CVE-2024-27018 8.2 HIGH netfilter: br_netfilter: skip conntrack input hook for promisc packets
CVE-2024-26936 8.2 HIGH ksmbd: validate request buffer size in smb2_allocate_rsp_buf()
CVE-2024-26980 8.2 HIGH ksmbd: fix slab-out-of-bounds in smb2_allocate_rsp_buf
CVE-2024-26954 8.1 HIGH ksmbd: fix slab-out-of-bounds in smb_strndup_from_utf16()
CVE-2024-26994 7.8 HIGH speakup: Avoid crash on very long word
CVE-2024-26966 7.8 HIGH clk: qcom: mmcc-apq8084: fix terminating of frequency table arrays
CVE-2024-26974 7.8 HIGH crypto: qat - resolve race condition during AER recovery
CVE-2024-26976 7.8 HIGH KVM: Always flush async #PF workqueue when vCPU is being destroyed
CVE-2024-27062 7.8 HIGH nouveau: lock the client object tree.
CVE-2024-27061 7.8 HIGH crypto: sun8i-ce - Fix use after free in unprepare
CVE-2024-26983 7.8 HIGH bootconfig: use memblock_free_late to free xbc memory to buddy
CVE-2024-27058 7.8 HIGH tmpfs: fix race on handling dquot rbtree
CVE-2024-27056 7.8 HIGH wifi: iwlwifi: mvm: ensure offloading TID queue exists
CVE-2024-27017 7.8 HIGH netfilter: nft_set_pipapo: walk over current view on netlink dump

Showing top 20 of 159 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2024-26960

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