mm/hugetlb: fix list corruption in allocate_file_region_entries()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74518
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 13:17:56 UTC
Updated2026-08-15 13:17:56 UTC
DescriptionIn 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d3ec7b6e09e512ba902b86bcca2c512fb06d492f 62e1c2741a4d923d9854efd5927a6212aad7a187 git Not specified
CNA Linux Linux affected d3ec7b6e09e512ba902b86bcca2c512fb06d492f 587a0accc2b4fccc5cf7baf0fe34e50efde51f9c git Not specified
CNA Linux Linux affected d3ec7b6e09e512ba902b86bcca2c512fb06d492f 126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df git Not specified
CNA Linux Linux affected d3ec7b6e09e512ba902b86bcca2c512fb06d492f ac1bb7fd45088d0db57a22ce7729f258ebd63cf5 git Not specified
CNA Linux Linux affected d3ec7b6e09e512ba902b86bcca2c512fb06d492f dd9623f58ec702a07b2d67179d6fcea79c52231a git Not specified
CNA Linux Linux affected 5.10 Not specified
CNA Linux Linux unaffected 5.10 semver Not specified
CNA Linux Linux unaffected 6.6.151 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.103 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.44 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.8 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc6 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/dd9623f58ec702a07b2d67179d6fcea79c52231a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/587a0accc2b4fccc5cf7baf0fe34e50efde51f9c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ac1bb7fd45088d0db57a22ce7729f258ebd63cf5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/62e1c2741a4d923d9854efd5927a6212aad7a187 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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