Security assessments indicate that CVE-2024-40949 presents a notable risk, potentially requiring prompt mitigation.
Status: Analyzed
Last updated: 🕣 06 Oct 2025, 20:47 UTC
Originally published on: 🕐 12 Jul 2024, 13:15 UTC
Time between publication and last update: 451 days
CVSS Release: version 3
nvd@nist.gov
Primary
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVE-2024-40949: In the Linux kernel, the following vulnerability has been resolved: mm: shmem: fix getting incorrect lruvec when replacing a shmem folio When testing shmem swapin, I encountered the warning below on my machine. The reason is that replacing an old shmem folio with a new one causes mem_cgroup_migrate() to clear the old folio's memcg data. As a result, the old folio cannot get the correct memcg's lruvec needed to remove itself from the LRU list when it is being freed. This could lead to possible serious problems, such as LRU list crashes due to holding the wrong LRU lock, and incorrect LRU statistics. To fix this issue, we can fallback to use the mem_cgroup_replace_folio() to replace the old shmem folio. [ 5241.100311] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5d9960 [ 5241.100317] head: order:4 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 [ 5241.100319] flags: 0x17fffe0000040068(uptodate|lru|head|swapbacked|node=0|zone=2|lastcpupid=0x3ffff) [ 5241.100323] raw: 17fffe0000040068 fffffdffd6687948 fffffdffd69ae008 0000000000000000 [ 5241.100325] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 [ 5241.100326] head: 17fffe0000040068 fffffdffd6687948 fffffdffd69ae008 0000000000000000 [ 5241.100327] head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 [ 5241.100328] head: 17fffe0000000204 fffffdffd6665801 ffffffffffffffff 0000000000000000 [ 5241.100329] head: 0000000a00000010 0000000000000000 00000000ffffffff 0000000000000000 [ 5241.100330] page dumped because: VM_WARN_ON_ONCE_FOLIO(!memcg && !mem_cgroup_disabled()) [ 5241.100338] ------------[ cut here ]------------ [ 5241.100339] WARNING: CPU: 19 PID: 78402 at include/linux/memcontrol.h:775 folio_lruvec_lock_irqsave+0x140/0x150 [...] [ 5241.100374] pc : folio_lruvec_lock_irqsave+0x140/0x150 [ 5241.100375] lr : folio_lruvec_lock_irqsave+0x138/0x150 [ 5241.100376] sp : ffff80008b38b930 [...] [ 5241.100398] Call trace: [ 5241.100399] folio_lruvec_lock_irqsave+0x140/0x150 [ 5241.100401] __page_cache_release+0x90/0x300 [ 5241.100404] __folio_put+0x50/0x108 [ 5241.100406] shmem_replace_folio+0x1b4/0x240 [ 5241.100409] shmem_swapin_folio+0x314/0x528 [ 5241.100411] shmem_get_folio_gfp+0x3b4/0x930 [ 5241.100412] shmem_fault+0x74/0x160 [ 5241.100414] __do_fault+0x40/0x218 [ 5241.100417] do_shared_fault+0x34/0x1b0 [ 5241.100419] do_fault+0x40/0x168 [ 5241.100420] handle_pte_fault+0x80/0x228 [ 5241.100422] __handle_mm_fault+0x1c4/0x440 [ 5241.100424] handle_mm_fault+0x60/0x1f0 [ 5241.100426] do_page_fault+0x120/0x488 [ 5241.100429] do_translation_fault+0x4c/0x68 [ 5241.100431] do_mem_abort+0x48/0xa0 [ 5241.100434] el0_da+0x38/0xc0 [ 5241.100436] el0t_64_sync_handler+0x68/0xc0 [ 5241.100437] el0t_64_sync+0x14c/0x150 [ 5241.100439] ---[ end trace 0000000000000000 ]--- [baolin.wang@linux.alibaba.com: remove less helpful comments, per Matthew]
The exploitability of CVE-2024-40949 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
CVE-2024-40949 presents an accessible attack vector with minimal effort required. Restricting access controls and implementing security updates are critical to reducing exploitation risks.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2024-40949, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2024-40949, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
The EPSS score estimates the probability that this vulnerability will be exploited in the near future.
EPSS Score: 0.043% (probability of exploit)
EPSS Percentile: 12.0%
(lower percentile = lower relative risk)
This vulnerability is less risky than approximately 88.0% of others.
NVD-CWE-noinfo
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