In the Linux kernel, the following vulnerability has been resolved:
mm/hugetlb: fix list corruption in allocate_file_region_entries()
allocate_file_region_entries() tops up resv->region_cache with freshly
allocated file_region descriptors. The allocation uses GFP_KERNEL, so
resv->lock is dropped around it: the new entries are gathered on a
stack-local list head, allocated_regions, and spliced into
resv->region_cache once the lock is re-acquired.
The splice used list_splice(), which moves the entries but does not
re-initialize the source head, so allocated_regions is left pointing at an
entry that now lives on resv->region_cache. The top-up runs in a while
loop that re-checks the cache deficit after re-acquiring the lock. For a
shared mapping the resv_map is shared by every mapper of the hugetlbfs
inode, so a concurrent region_chg()/region_add()/region_del() on the same
resv_map can consume cache entries during the unlocked window and force a
second iteration. That iteration calls list_add() on the stale head and
corrupts the list; with CONFIG_DEBUG_LIST the __list_add_valid() check
trips:
list_add corruption. next->prev should be prev (ffffc900011ff7f8),
but was ffff88814c281460. (next=ffff88814c545640).
kernel BUG at lib/list_debug.c:31!
allocate_file_region_entries+0x191/0x420
region_chg+0x267/0x300
hugetlb_reserve_pages+0x387/0xc80
hugetlbfs_file_mmap+0x2ce/0x3f0
mmap_region+0x1348/0x1a80
do_mmap+0x85e/0xb90
vm_mmap_pgoff+0x18c/0x330
ksys_mmap_pgoff+0x2a1/0x3e0
do_syscall_64+0xd7/0x420
Without CONFIG_DEBUG_LIST the bad list_add() silently links a kernel-stack
address into resv->region_cache, leading to later use-after-free.
This was observed as a real host panic on a dense KVM host where a QEMU
guest-RAM hugetlbfs file was mapped MAP_SHARED by both QEMU and a separate
SPDK/DPDK vhost-user target, generating concurrent region_* traffic on one
shared resv_map.
Use list_splice_init() so the source head is re-initialized empty after
each splice, making the retry loop safe.
mm/hugetlb: fix list corruption in allocate_file_region_entries()
allocate_file_region_entries() tops up resv->region_cache with freshly
allocated file_region descriptors. The allocation uses GFP_KERNEL, so
resv->lock is dropped around it: the new entries are gathered on a
stack-local list head, allocated_regions, and spliced into
resv->region_cache once the lock is re-acquired.
The splice used list_splice(), which moves the entries but does not
re-initialize the source head, so allocated_regions is left pointing at an
entry that now lives on resv->region_cache. The top-up runs in a while
loop that re-checks the cache deficit after re-acquiring the lock. For a
shared mapping the resv_map is shared by every mapper of the hugetlbfs
inode, so a concurrent region_chg()/region_add()/region_del() on the same
resv_map can consume cache entries during the unlocked window and force a
second iteration. That iteration calls list_add() on the stale head and
corrupts the list; with CONFIG_DEBUG_LIST the __list_add_valid() check
trips:
list_add corruption. next->prev should be prev (ffffc900011ff7f8),
but was ffff88814c281460. (next=ffff88814c545640).
kernel BUG at lib/list_debug.c:31!
allocate_file_region_entries+0x191/0x420
region_chg+0x267/0x300
hugetlb_reserve_pages+0x387/0xc80
hugetlbfs_file_mmap+0x2ce/0x3f0
mmap_region+0x1348/0x1a80
do_mmap+0x85e/0xb90
vm_mmap_pgoff+0x18c/0x330
ksys_mmap_pgoff+0x2a1/0x3e0
do_syscall_64+0xd7/0x420
Without CONFIG_DEBUG_LIST the bad list_add() silently links a kernel-stack
address into resv->region_cache, leading to later use-after-free.
This was observed as a real host panic on a dense KVM host where a QEMU
guest-RAM hugetlbfs file was mapped MAP_SHARED by both QEMU and a separate
SPDK/DPDK vhost-user target, generating concurrent region_* traffic on one
shared resv_map.
Use list_splice_init() so the source head is re-initialized empty after
each splice, making the retry loop safe.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
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| Linux | Linux | affected |
|
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Fixes
Solution
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Workaround
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References
History
Sat, 15 Aug 2026 12:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: fix list corruption in allocate_file_region_entries() allocate_file_region_entries() tops up resv->region_cache with freshly allocated file_region descriptors. The allocation uses GFP_KERNEL, so resv->lock is dropped around it: the new entries are gathered on a stack-local list head, allocated_regions, and spliced into resv->region_cache once the lock is re-acquired. The splice used list_splice(), which moves the entries but does not re-initialize the source head, so allocated_regions is left pointing at an entry that now lives on resv->region_cache. The top-up runs in a while loop that re-checks the cache deficit after re-acquiring the lock. For a shared mapping the resv_map is shared by every mapper of the hugetlbfs inode, so a concurrent region_chg()/region_add()/region_del() on the same resv_map can consume cache entries during the unlocked window and force a second iteration. That iteration calls list_add() on the stale head and corrupts the list; with CONFIG_DEBUG_LIST the __list_add_valid() check trips: list_add corruption. next->prev should be prev (ffffc900011ff7f8), but was ffff88814c281460. (next=ffff88814c545640). kernel BUG at lib/list_debug.c:31! allocate_file_region_entries+0x191/0x420 region_chg+0x267/0x300 hugetlb_reserve_pages+0x387/0xc80 hugetlbfs_file_mmap+0x2ce/0x3f0 mmap_region+0x1348/0x1a80 do_mmap+0x85e/0xb90 vm_mmap_pgoff+0x18c/0x330 ksys_mmap_pgoff+0x2a1/0x3e0 do_syscall_64+0xd7/0x420 Without CONFIG_DEBUG_LIST the bad list_add() silently links a kernel-stack address into resv->region_cache, leading to later use-after-free. This was observed as a real host panic on a dense KVM host where a QEMU guest-RAM hugetlbfs file was mapped MAP_SHARED by both QEMU and a separate SPDK/DPDK vhost-user target, generating concurrent region_* traffic on one shared resv_map. Use list_splice_init() so the source head is re-initialized empty after each splice, making the retry loop safe. | |
| Title | mm/hugetlb: fix list corruption in allocate_file_region_entries() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-15T12:27:37.480Z
Reserved: 2026-08-15T05:44:03.910Z
Link: CVE-2026-74518
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
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Weaknesses
No weakness.