# CVE-2024-40949: linux: In the Linux kernel, the following vulnerability has been resolved:  mm: shmem: fix getting incorrect lruvec when rep...

CVE-2024-40949 is fixed in linux on 1 platform, first by DEBIAN-CVE-2024-40949, released July 12, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2024-40949
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0022
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 12, 2024

## Description

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]

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.9.7-1 | [DEBIAN-CVE-2024-40949](https://patchblox.com/security/data/fix/linux/debian-cve-2024-40949.md) | Jul 12, 2024 |
| Linux | linux Debian 14 | 6.9.7-1 | [DEBIAN-CVE-2024-40949](https://patchblox.com/security/data/fix/linux/debian-cve-2024-40949.md) | Jul 12, 2024 |

---

Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.