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linux/include
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Lorenzo Stoakes (ARM) a1c7570ced x86/mm/pat: Acquire init_mm write lock on collapse to avoid UAF 
x86 implements page attribute modification using its Change Page
Attributes (CPA) mechanism.

This tracks properties of ranges such as cache mode through x86 page
attributes, and as part of that logic manipulates kernel page tables.

Since commit:

  41d88484c7 ("x86/mm/pat: restore large ROX pages after fragmentation")

ranges of kernel page table entries can be collapsed into
huge page table entries as part of this logic.

As part of this collapse, it frees the page tables which the collapsed
entries previously pointed to, and it does so without any relevant locks
being held to preclude concurrent kernel page table walkers.

The only way this code can be reached is if CPA_COLLAPSE is specified, and
this is only set in set_memory_rox() via:

set_memory_rox()
-> change_page_attr_set_clr()
-> cpa_flush()
-> cpa_collapse_large_pages()

Notable users of this are execmem and BPF when manipulating executable
mappings.

However, this is problematic for ptdump as it walks ranges it does not own
and thus runs the risk of a use-after-free on page tables freed underneath
it.

In addition, concurrent CPA collapse operations are possible which can also
cause races.

Resolve the issue by acquiring the mmap write lock on init_mm across the
whole operation.

It is safe to acquire a sleeping lock as all the callers invoke
set_memory_rox() from process context and in any case,
change_page_attr_set_clr() calls vm_unmap_alias() which ultimately takes a
mutex, disallowing atomic context here.

Fixes: 41d88484c7 ("x86/mm/pat: restore large ROX pages after fragmentation")
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Will Deacon <will@kernel.org>
Reviewed-by: David Carlier <devnexen@gmail.com>
Tested-by: Atish Patra <atishp@meta.com>
Tested-by: Nikunj A Dadhania <nikunj@amd.com>
Cc:stable@vger.kernel.org
Link: https://patch.msgid.link/20260813-cpa-fixes-v2-1-39b4ff90f91d@kernel.org
2026-09-09 08:38:56 +02:00
..
acpi More ACPI support updates for 7.3-rc1 2026-08-26 14:06:08 -07:00
asm-generic kho: make boot time huge page allocation work nicely with KHO 2026-08-23 09:17:38 -07:00
clocksource hyperv-next for v7.3-rc1 2026-08-26 16:47:40 -07:00
crypto This update includes the following changes: 2026-08-19 17:25:42 -07:00
cxl Merge branch 'for-7.3/cxl-port-err-prep' into cxl-for-next 2026-08-05 13:55:07 -07:00
drm Linux 7.2 2026-08-20 10:58:44 +10:00
dt-bindings sound fixes for 7.3-rc1 2026-08-28 10:01:02 -07:00
hyperv
keys tpm: Initial step to reorganize TPM public headers 2026-08-25 18:13:35 +03:00
kunit gpio updates for v7.3-rc1 2026-08-19 09:10:07 -07:00
kvm KVM/arm64 changes for 7.3 2026-08-24 12:42:07 -04:00
linux x86/mm/pat: Acquire init_mm write lock on collapse to avoid UAF 2026-09-09 08:38:56 +02:00
math-emu
media
memory
misc
net Including fixes from Bluetooth, IPSec and Netfilter. 2026-08-27 13:53:43 -07:00
pcmcia
ras
rdma
rv mm.git review status for linus..mm-stable 2026-08-27 09:17:06 -07:00
scsi SCSI updates for 7.3 2026-08-29 11:55:36 -07:00
soc Mostly the usual clk driver updates and new SoC additions plus non-critical 2026-08-26 11:14:30 -07:00
sound ALSA: rawmidi: Another workaround for false-positive mutex lockdep warning 2026-08-25 15:55:37 +02:00
target usb: gadget: f_tcm: keep port count until LUN teardown completes 2026-08-14 10:49:21 +09:00
trace f2fs-for-7.3-rc1 2026-08-28 10:48:48 -07:00
uapi drm next/fixes for 7.3-rc1 2026-08-28 16:37:55 -07:00
ufs Merge patch series "scsi: ufs: Add support for the aggregated read query opcode" 2026-08-07 11:34:35 -04:00
vdso vDSO: Make clockmode constants available without CONFIG_GENERIC_GETTIMEOFDAY 2026-08-10 16:25:21 +02:00
video fbdev: maxine: fix 64-bit build error 2026-08-20 23:45:07 +02:00
xen xen: Drop CONFIG_XEN_AUTO_XLATE 2026-08-06 13:18:32 +02:00
Kbuild