// For flags

CVE-2021-47632

powerpc/set_memory: Avoid spinlock recursion in change_page_attr()

Time Line
Published
2024-03-19
Updated
2024-03-19
Firt exploit
2024-03-19
Overview
Descriptions (1)
MITRE
CWE (0)
CAPEC (-)
Risk
CVSS Score
-
SSVC
-
KEV
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EPSS
Affected Products (-)
Vendors (1)
linux
Products (1)
linux_kernel
Versions (4)
< 5.15.34, < 5.16.20, < 5.17.3, < 5.18
Intel Resources (-)
Advisories (-)
-
Exploits (-)
-
Plugins (-)
-
References (4)
General (-)
Exploits & POcs (-)
Patches (4)
kernel
Advisories (-)
Summary
Descriptions

In the Linux kernel, the following vulnerability has been resolved: powerpc/set_memory: Avoid spinlock recursion in change_page_attr() Commit 1f9ad21c3b38 ("powerpc/mm: Implement set_memory() routines")
included a spin_lock() to change_page_attr() in order to
safely perform the three step operations. But then
commit 9f7853d7609d ("powerpc/mm: Fix set_memory_*() against
concurrent accesses") modify it to use pte_update() and do
the operation safely against concurrent access. In the meantime, Maxime reported some spinlock recursion. [ 15.351649] BUG: spinlock recursion on CPU#0, kworker/0:2/217
[ 15.357540] lock: init_mm+0x3c/0x420, .magic: dead4ead, .owner: kworker/0:2/217, .owner_cpu: 0
[ 15.366563] CPU: 0 PID: 217 Comm: kworker/0:2 Not tainted 5.15.0+ #523
[ 15.373350] Workqueue: events do_free_init
[ 15.377615] Call Trace:
[ 15.380232] [e4105ac0] [800946a4] do_raw_spin_lock+0xf8/0x120 (unreliable)
[ 15.387340] [e4105ae0] [8001f4ec] change_page_attr+0x40/0x1d4
[ 15.393413] [e4105b10] [801424e0] __apply_to_page_range+0x164/0x310
[ 15.400009] [e4105b60] [80169620] free_pcp_prepare+0x1e4/0x4a0
[ 15.406045] [e4105ba0] [8016c5a0] free_unref_page+0x40/0x2b8
[ 15.411979] [e4105be0] [8018724c] kasan_depopulate_vmalloc_pte+0x6c/0x94
[ 15.418989] [e4105c00] [801424e0] __apply_to_page_range+0x164/0x310
[ 15.425451] [e4105c50] [80187834] kasan_release_vmalloc+0xbc/0x134
[ 15.431898] [e4105c70] [8015f7a8] __purge_vmap_area_lazy+0x4e4/0xdd8
[ 15.438560] [e4105d30] [80160d10] _vm_unmap_aliases.part.0+0x17c/0x24c
[ 15.445283] [e4105d60] [801642d0] __vunmap+0x2f0/0x5c8
[ 15.450684] [e4105db0] [800e32d0] do_free_init+0x68/0x94
[ 15.456181] [e4105dd0] [8005d094] process_one_work+0x4bc/0x7b8
[ 15.462283] [e4105e90] [8005d614] worker_thread+0x284/0x6e8
[ 15.468227] [e4105f00] [8006aaec] kthread+0x1f0/0x210
[ 15.473489] [e4105f40] [80017148] ret_from_kernel_thread+0x14/0x1c Remove the read / modify / write sequence to make the operation atomic
and remove the spin_lock() in change_page_attr(). To do the operation atomically, we can't use pte modification helpers
anymore. Because all platforms have different combination of bits, it
is not easy to use those bits directly. But all have the
_PAGE_KERNEL_{RO/ROX/RW/RWX} set of flags. All we need it to compare
two sets to know which bits are set or cleared. For instance, by comparing _PAGE_KERNEL_ROX and _PAGE_KERNEL_RO you
know which bit gets cleared and which bit get set when changing exec
permission.

*Credits: N/A
CVSS Scores
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* Organization's Worst-case Scenario
Timeline
  • 2025-02-26 CVE Reserved
  • 2025-02-26 CVE Published
  • 2025-02-26 CVE Updated
  • ---------- EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
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Threat Intelligence Resources (0)
Security Advisory details:

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Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 < 5.15.34
Search vendor "Linux" for product "Linux Kernel" and version " < 5.15.34"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 < 5.16.20
Search vendor "Linux" for product "Linux Kernel" and version " < 5.16.20"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 < 5.17.3
Search vendor "Linux" for product "Linux Kernel" and version " < 5.17.3"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 < 5.18
Search vendor "Linux" for product "Linux Kernel" and version " < 5.18"
en
Affected