CVE-2022-49052

MEDIUM EPSS 18.3%
Published Feb 26, 20251y ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Feb 26, 2025 1y ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: mm: fix unexpected zeroed page mapping with zram swap Two processes under CLONE_VM cloning, user process can be corrupted by seeing zeroed page unexpectedly. CPU A CPU B do_swap_page do_swap_page SWP_SYNCHRONOUS_IO path SWP_SYNCHRONOUS_IO path swap_readpage valid data swap_slot_free_notify delete zram entry swap_readpage zeroed(invalid) data pte_lock map the *zero data* to userspace pte_unlock pte_lock if (!pte_same) goto out_nomap; pte_unlock return and next refault will read zeroed data The swap_slot_free_notify is bogus for CLONE_VM case since it doesn't increase the refcount of swap slot at copy_mm so it couldn't catch up whether it's safe or not to discard data from backing device. In the case, only the lock it could rely on to synchronize swap slot freeing is page table lock. Thus, this patch gets rid of the swap_slot_free_notify function. With this patch, CPU A will see correct data. CPU A CPU B do_swap_page do_swap_page SWP_SYNCHRONOUS_IO path SWP_SYNCHRONOUS_IO path swap_readpage original data pte_lock map the original data swap_free swap_range_free bd_disk->fops->swap_slot_free_notify swap_readpage read zeroed data pte_unlock pte_lock if (!pte_same) goto out_nomap; pte_unlock return on next refault will see mapped data by CPU B The concern of the patch would increase memory consumption since it could keep wasted memory with compressed form in zram as well as uncompressed form in address space. However, most of cases of zram uses no readahead and do_swap_page is followed by swap_free so it will free the compressed form from in zram quickly.

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
18.3% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Affected Products 7

VendorProductVersionRange
linuxlinux_kernel*≥4.15  –  <4.19.242
linuxlinux_kernel*≥4.20  –  <5.4.193
linuxlinux_kernel*≥5.5  –  <5.10.112
linuxlinux_kernel*≥5.11  –  <5.15.35
linuxlinux_kernel*≥5.16  –  <5.17.4
linuxlinux_kernel5.18any
linuxlinux_kernel5.18any

References 6

  • git.kernel.org https://git.kernel.org/stable/c/12ba1d38115a101c45d8e0ca3aa1181fd148e57f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/20ed94f8181a25212e7404e44958e234f407624b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/afac4b88699a06c8b9369f9d759a1ec3c254b788
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e914d8f00391520ecc4495dd0ca0124538ab7119
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f098f8b9820fe3f2e41aefc4329dfe8a3859d1c1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f86d55cf616199404c05f5b0c5c41b17351baa02
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/12ba1d38115a101c45d8e0ca3aa1181fd148e57f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/20ed94f8181a25212e7404e44958e234f407624b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/afac4b88699a06c8b9369f9d759a1ec3c254b788
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e914d8f00391520ecc4495dd0ca0124538ab7119
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f098f8b9820fe3f2e41aefc4329dfe8a3859d1c1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f86d55cf616199404c05f5b0c5c41b17351baa02
    Patch