mm/vma: fix memory leak in __mmap_region()

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Summary

CVECVE-2026-31654
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-24 15:16:44 UTC
Updated2026-04-27 20:16:27 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm/vma: fix memory leak in __mmap_region() commit 605f6586ecf7 ("mm/vma: do not leak memory when .mmap_prepare swaps the file") handled the success path by skipping get_file() via file_doesnt_need_get, but missed the error path. When /dev/zero is mmap'd with MAP_SHARED, mmap_zero_prepare() calls shmem_zero_setup_desc() which allocates a new shmem file to back the mapping. If __mmap_new_vma() subsequently fails, this replacement file is never fput()'d - the original is released by ksys_mmap_pgoff(), but nobody releases the new one. Add fput() for the swapped file in the error path. Reproducible with fault injection. FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 1 CPU: 2 UID: 0 PID: 366 Comm: syz.7.14 Not tainted 7.0.0-rc6 #2 PREEMPT(full) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x164/0x1f0 should_fail_ex+0x525/0x650 should_failslab+0xdf/0x140 kmem_cache_alloc_noprof+0x78/0x630 vm_area_alloc+0x24/0x160 __mmap_region+0xf6b/0x2660 mmap_region+0x2eb/0x3a0 do_mmap+0xc79/0x1240 vm_mmap_pgoff+0x252/0x4c0 ksys_mmap_pgoff+0xf8/0x120 __x64_sys_mmap+0x12a/0x190 do_syscall_64+0xa9/0x580 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak) BUG: memory leak unreferenced object 0xffff8881118aca80 (size 360): comm "syz.7.14", pid 366, jiffies 4294913255 hex dump (first 32 bytes): 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... ff ff ff ff ff ff ff ff c0 28 4d ae ff ff ff ff .........(M..... backtrace (crc db0f53bc): kmem_cache_alloc_noprof+0x3ab/0x630 alloc_empty_file+0x5a/0x1e0 alloc_file_pseudo+0x135/0x220 __shmem_file_setup+0x274/0x420 shmem_zero_setup_desc+0x9c/0x170 mmap_zero_prepare+0x123/0x140 __mmap_region+0xdda/0x2660 mmap_region+0x2eb/0x3a0 do_mmap+0xc79/0x1240 vm_mmap_pgoff+0x252/0x4c0 ksys_mmap_pgoff+0xf8/0x120 __x64_sys_mmap+0x12a/0x190 do_syscall_64+0xa9/0x580 entry_SYSCALL_64_after_hwframe+0x76/0x7e Found by syzkaller.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.000180000 probability, percentile 0.049720000 (date 2026-04-27)

Problem Types: CWE-401

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All
Operating System Linux Linux Kernel 6.19 - All All
Operating System Linux Linux Kernel 7.0 rc1 All All
Operating System Linux Linux Kernel 7.0 rc2 All All
Operating System Linux Linux Kernel 7.0 rc3 All All
Operating System Linux Linux Kernel 7.0 rc4 All All
Operating System Linux Linux Kernel 7.0 rc5 All All
Operating System Linux Linux Kernel 7.0 rc6 All All
Operating System Linux Linux Kernel 7.0 rc7 All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 605f6586ecf78395f0185ab24c368fb46a06e434 61fc8eaf2ab214b32c7bce52597c80cf0ca41ada git Not specified
CNA Linux Linux affected 605f6586ecf78395f0185ab24c368fb46a06e434 894f99eb535edc4514f756818f3c4f688ba53a59 git Not specified
CNA Linux Linux affected 6.19 Not specified
CNA Linux Linux unaffected 6.19 semver Not specified
CNA Linux Linux unaffected 6.19.13 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/61fc8eaf2ab214b32c7bce52597c80cf0ca41ada 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/894f99eb535edc4514f756818f3c4f688ba53a59 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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