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Ubuntu: (Multiple Advisories) (CVE-2024-26960): Linux kernel vulnerabilities

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Ubuntu: (Multiple Advisories) (CVE-2024-26960): Linux kernel vulnerabilities

Severity
4
CVSS
(AV:L/AC:M/Au:N/C:P/I:P/A:P)
Published
05/01/2024
Created
07/02/2024
Added
07/01/2024
Modified
11/20/2024

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<-----

Solution(s)

  • ubuntu-upgrade-linux-image-4-15-0-1136-oracle
  • ubuntu-upgrade-linux-image-4-15-0-1157-kvm
  • ubuntu-upgrade-linux-image-4-15-0-1167-gcp
  • ubuntu-upgrade-linux-image-4-15-0-1174-aws
  • ubuntu-upgrade-linux-image-4-15-0-1182-azure
  • ubuntu-upgrade-linux-image-4-15-0-230-generic
  • ubuntu-upgrade-linux-image-4-15-0-230-lowlatency
  • ubuntu-upgrade-linux-image-5-15-0-1035-xilinx-zynqmp
  • ubuntu-upgrade-linux-image-5-15-0-1048-gkeop
  • ubuntu-upgrade-linux-image-5-15-0-1058-ibm
  • ubuntu-upgrade-linux-image-5-15-0-1058-raspi
  • ubuntu-upgrade-linux-image-5-15-0-1060-intel-iotg
  • ubuntu-upgrade-linux-image-5-15-0-1060-nvidia
  • ubuntu-upgrade-linux-image-5-15-0-1060-nvidia-lowlatency
  • ubuntu-upgrade-linux-image-5-15-0-1062-gke
  • ubuntu-upgrade-linux-image-5-15-0-1062-kvm
  • ubuntu-upgrade-linux-image-5-15-0-1063-oracle
  • ubuntu-upgrade-linux-image-5-15-0-1064-gcp
  • ubuntu-upgrade-linux-image-5-15-0-1065-aws
  • ubuntu-upgrade-linux-image-5-15-0-1065-gcp
  • ubuntu-upgrade-linux-image-5-15-0-1068-azure
  • ubuntu-upgrade-linux-image-5-15-0-1068-azure-fde
  • ubuntu-upgrade-linux-image-5-15-0-116-generic
  • ubuntu-upgrade-linux-image-5-15-0-116-generic-64k
  • ubuntu-upgrade-linux-image-5-15-0-116-generic-lpae
  • ubuntu-upgrade-linux-image-5-15-0-116-lowlatency
  • ubuntu-upgrade-linux-image-5-15-0-116-lowlatency-64k
  • ubuntu-upgrade-linux-image-5-4-0-1044-iot
  • ubuntu-upgrade-linux-image-5-4-0-1053-xilinx-zynqmp
  • ubuntu-upgrade-linux-image-5-4-0-1081-ibm
  • ubuntu-upgrade-linux-image-5-4-0-1094-bluefield
  • ubuntu-upgrade-linux-image-5-4-0-1101-gkeop
  • ubuntu-upgrade-linux-image-5-4-0-1118-raspi
  • ubuntu-upgrade-linux-image-5-4-0-1122-kvm
  • ubuntu-upgrade-linux-image-5-4-0-1133-oracle
  • ubuntu-upgrade-linux-image-5-4-0-1134-aws
  • ubuntu-upgrade-linux-image-5-4-0-1138-gcp
  • ubuntu-upgrade-linux-image-5-4-0-1139-azure
  • ubuntu-upgrade-linux-image-5-4-0-198-generic
  • ubuntu-upgrade-linux-image-5-4-0-198-generic-lpae
  • ubuntu-upgrade-linux-image-5-4-0-198-lowlatency
  • ubuntu-upgrade-linux-image-6-8-0-1004-gke
  • ubuntu-upgrade-linux-image-6-8-0-1005-raspi
  • ubuntu-upgrade-linux-image-6-8-0-1006-ibm
  • ubuntu-upgrade-linux-image-6-8-0-1006-oem
  • ubuntu-upgrade-linux-image-6-8-0-1006-oracle
  • ubuntu-upgrade-linux-image-6-8-0-1006-oracle-64k
  • ubuntu-upgrade-linux-image-6-8-0-1008-azure
  • ubuntu-upgrade-linux-image-6-8-0-1008-azure-fde
  • ubuntu-upgrade-linux-image-6-8-0-1008-gcp
  • ubuntu-upgrade-linux-image-6-8-0-1009-aws
  • ubuntu-upgrade-linux-image-6-8-0-35-generic
  • ubuntu-upgrade-linux-image-6-8-0-35-generic-64k
  • ubuntu-upgrade-linux-image-6-8-0-35-lowlatency
  • ubuntu-upgrade-linux-image-6-8-0-35-lowlatency-64k
  • ubuntu-upgrade-linux-image-aws
  • ubuntu-upgrade-linux-image-aws-hwe
  • ubuntu-upgrade-linux-image-aws-lts-18-04
  • ubuntu-upgrade-linux-image-aws-lts-20-04
  • ubuntu-upgrade-linux-image-aws-lts-22-04
  • ubuntu-upgrade-linux-image-azure
  • ubuntu-upgrade-linux-image-azure-cvm
  • ubuntu-upgrade-linux-image-azure-fde
  • ubuntu-upgrade-linux-image-azure-fde-lts-22-04
  • ubuntu-upgrade-linux-image-azure-lts-18-04
  • ubuntu-upgrade-linux-image-azure-lts-20-04
  • ubuntu-upgrade-linux-image-azure-lts-22-04
  • ubuntu-upgrade-linux-image-bluefield
  • ubuntu-upgrade-linux-image-gcp
  • ubuntu-upgrade-linux-image-gcp-lts-18-04
  • ubuntu-upgrade-linux-image-gcp-lts-20-04
  • ubuntu-upgrade-linux-image-gcp-lts-22-04
  • ubuntu-upgrade-linux-image-generic
  • ubuntu-upgrade-linux-image-generic-64k
  • ubuntu-upgrade-linux-image-generic-64k-hwe-20-04
  • ubuntu-upgrade-linux-image-generic-64k-hwe-24-04
  • ubuntu-upgrade-linux-image-generic-hwe-16-04
  • ubuntu-upgrade-linux-image-generic-hwe-18-04
  • ubuntu-upgrade-linux-image-generic-hwe-20-04
  • ubuntu-upgrade-linux-image-generic-hwe-24-04
  • ubuntu-upgrade-linux-image-generic-lpae
  • ubuntu-upgrade-linux-image-generic-lpae-hwe-20-04
  • ubuntu-upgrade-linux-image-gke
  • ubuntu-upgrade-linux-image-gke-5-15
  • ubuntu-upgrade-linux-image-gkeop
  • ubuntu-upgrade-linux-image-gkeop-5-15
  • ubuntu-upgrade-linux-image-gkeop-5-4
  • ubuntu-upgrade-linux-image-ibm
  • ubuntu-upgrade-linux-image-ibm-classic
  • ubuntu-upgrade-linux-image-ibm-lts-20-04
  • ubuntu-upgrade-linux-image-ibm-lts-24-04
  • ubuntu-upgrade-linux-image-intel
  • ubuntu-upgrade-linux-image-intel-iotg
  • ubuntu-upgrade-linux-image-kvm
  • ubuntu-upgrade-linux-image-lowlatency
  • ubuntu-upgrade-linux-image-lowlatency-64k
  • ubuntu-upgrade-linux-image-lowlatency-64k-hwe-20-04
  • ubuntu-upgrade-linux-image-lowlatency-hwe-16-04
  • ubuntu-upgrade-linux-image-lowlatency-hwe-18-04
  • ubuntu-upgrade-linux-image-lowlatency-hwe-20-04
  • ubuntu-upgrade-linux-image-nvidia
  • ubuntu-upgrade-linux-image-nvidia-lowlatency
  • ubuntu-upgrade-linux-image-oem
  • ubuntu-upgrade-linux-image-oem-20-04
  • ubuntu-upgrade-linux-image-oem-20-04b
  • ubuntu-upgrade-linux-image-oem-20-04c
  • ubuntu-upgrade-linux-image-oem-20-04d
  • ubuntu-upgrade-linux-image-oem-24-04
  • ubuntu-upgrade-linux-image-oem-24-04a
  • ubuntu-upgrade-linux-image-oem-osp1
  • ubuntu-upgrade-linux-image-oracle
  • ubuntu-upgrade-linux-image-oracle-64k
  • ubuntu-upgrade-linux-image-oracle-lts-18-04
  • ubuntu-upgrade-linux-image-oracle-lts-20-04
  • ubuntu-upgrade-linux-image-oracle-lts-22-04
  • ubuntu-upgrade-linux-image-raspi
  • ubuntu-upgrade-linux-image-raspi-hwe-18-04
  • ubuntu-upgrade-linux-image-raspi-nolpae
  • ubuntu-upgrade-linux-image-raspi2
  • ubuntu-upgrade-linux-image-snapdragon-hwe-18-04
  • ubuntu-upgrade-linux-image-virtual
  • ubuntu-upgrade-linux-image-virtual-hwe-16-04
  • ubuntu-upgrade-linux-image-virtual-hwe-18-04
  • ubuntu-upgrade-linux-image-virtual-hwe-20-04
  • ubuntu-upgrade-linux-image-virtual-hwe-24-04
  • ubuntu-upgrade-linux-image-xilinx-zynqmp

References

  • https://attackerkb.com/topics/cve-2024-26960
  • CVE - 2024-26960
  • USN-6816-1
  • USN-6817-1
  • USN-6817-2
  • USN-6817-3
  • USN-6878-1
  • USN-6898-1
  • USN-6898-2
  • USN-6898-3
  • USN-6898-4
  • USN-6917-1
  • USN-6919-1
  • USN-6927-1
  • USN-7019-1
  • USN-7069-1
  • USN-7069-2
  • USN-7073-1
  • USN-7073-2
  • USN-7119-1
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