In the Linux kernel, the following vulnerability has been resolved:
btrfs: zoned: fix use-after-free in dozonefinish()
Shinichiro reported the following use-after-free triggered by the device replace operation in fstests btrfs/070.
BTRFS info (device nullb1): scrub: finished on devid 1 with status: 0 ================================================================== BUG: KASAN: slab-use-after-free in dozonefinish+0x91a/0xb90 [btrfs] Read of size 8 at addr ffff8881543c8060 by task btrfs-cleaner/3494007
CPU: 0 PID: 3494007 Comm: btrfs-cleaner Tainted: G W 6.8.0-rc5-kts #1 Hardware name: Supermicro Super Server/X11SPi-TF, BIOS 3.3 02/21/2020 Call Trace: <TASK> dumpstacklvl+0x5b/0x90 printreport+0xcf/0x670 ? _virtaddrvalid+0x200/0x3e0 kasanreport+0xd8/0x110 ? dozonefinish+0x91a/0xb90 [btrfs] ? dozonefinish+0x91a/0xb90 [btrfs] dozonefinish+0x91a/0xb90 [btrfs] btrfsdeleteunusedbgs+0x5e1/0x1750 [btrfs] ? _pfxbtrfsdeleteunusedbgs+0x10/0x10 [btrfs] ? btrfsputroot+0x2d/0x220 [btrfs] ? btrfscleanonedeletedsnapshot+0x299/0x430 [btrfs] cleanerkthread+0x21e/0x380 [btrfs] ? _pfxcleanerkthread+0x10/0x10 [btrfs] kthread+0x2e3/0x3c0 ? _pfxkthread+0x10/0x10 retfromfork+0x31/0x70 ? _pfxkthread+0x10/0x10 retfromforkasm+0x1b/0x30 </TASK>
Allocated by task 3493983: kasansavestack+0x33/0x60 kasansavetrack+0x14/0x30 _kasankmalloc+0xaa/0xb0 btrfsallocdevice+0xb3/0x4e0 [btrfs] devicelistadd.constprop.0+0x993/0x1630 [btrfs] btrfsscanonedevice+0x219/0x3d0 [btrfs] btrfscontrolioctl+0x26e/0x310 [btrfs] _x64sysioctl+0x134/0x1b0 dosyscall64+0x99/0x190 entrySYSCALL64afterhwframe+0x6e/0x76
Freed by task 3494056: kasansavestack+0x33/0x60 kasansavetrack+0x14/0x30 kasansavefreeinfo+0x3f/0x60 poisonslabobject+0x102/0x170 _kasanslabfree+0x32/0x70 kfree+0x11b/0x320 btrfsrmdevreplacefreesrcdev+0xca/0x280 [btrfs] btrfsdevreplacefinishing+0xd7e/0x14f0 [btrfs] btrfsdevreplacebyioctl+0x1286/0x25a0 [btrfs] btrfsioctl+0xb27/0x57d0 [btrfs] _x64sysioctl+0x134/0x1b0 dosyscall64+0x99/0x190 entrySYSCALL64afterhwframe+0x6e/0x76
The buggy address belongs to the object at ffff8881543c8000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 96 bytes inside of freed 1024-byte region [ffff8881543c8000, ffff8881543c8400)
The buggy address belongs to the physical page: page:00000000fe2c1285 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1543c8 head:00000000fe2c1285 order:3 entiremapcount:0 nrpagesmapped:0 pincount:0 flags: 0x17ffffc0000840(slab|head|node=0|zone=2|lastcpupid=0x1fffff) pagetype: 0xffffffff() raw: 0017ffffc0000840 ffff888100042dc0 ffffea0019e8f200 dead000000000002 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8881543c7f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8881543c7f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8881543c8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881543c8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881543c8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
This UAF happens because we're accessing stale zone information of a already removed btrfsdevice in dozone_finish().
The sequence of events is as follows:
btrfsdevreplacestart btrfsscrubdev btrfsdevreplacefinishing btrfsdevreplaceupdatedeviceinmappingtree <-- devices replaced btrfsrmdevreplacefreesrcdev btrfsfreedevice <-- device freed
cleanerkthread btrfsdeleteunusedbgs btrfszonefinish dozonefinish <-- refers the freed device
The reason for this is that we're using a ---truncated---
{ "vanir_signatures": [ { "signature_version": "v1", "signature_type": "Function", "target": { "file": "fs/btrfs/zoned.c", "function": "do_zone_finish" }, "deprecated": false, "digest": { "length": 2461.0, "function_hash": "167769436227192270313270889154492827608" }, "id": "CVE-2024-26944-7a0fc14b", "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@1ec17ef59168a1a6f1105f5dc517f783839a5302" }, { "signature_version": "v1", "signature_type": "Line", "target": { "file": "fs/btrfs/zoned.c" }, "deprecated": false, "digest": { "line_hashes": [ "296485909753592348215590702035423973730", "168870151593064014731992782391427668111", "190967533391762100296047511119884918694", "305734183601165156642472393042807156580", "323872210325311784680431332968123191995", "313972715112378856992143936745060230737", "193133904891312589228743778978961858447", "184927299036527615121285700409138451935", "188505058886581550624062103115505177042", "317861302494051890453606535245178224207", "190880779094411461120938330537060698748", "231919902297431052914146251260368951868", "47094099555610417519285860738891533573", "9192431344743619849023820040554908090", "255095236668510372343636010412503553765", "228629650719081065619324853137458336104", "286204902269261971518091630826564952999", "54258316318111234017000329040542654330", "302968128323629531079358534310626904704", "241347700797313431415036782978803120782", "272312178184303810642642164517396017842", "151857170148406037400288183407776186752", "206271085107374343257231836085817140430", "5232601418819513270062322455642124182", "300612717105267491561522875306362084842", "172323547174712419865065231350217730156", "339382015342740949587980342968302258401", "86843803705924374476335200030445445761" ], "threshold": 0.9 }, "id": "CVE-2024-26944-b814f8f6", "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@1ec17ef59168a1a6f1105f5dc517f783839a5302" }, { "signature_version": "v1", "signature_type": "Line", "target": { "file": "fs/btrfs/zoned.c" }, "deprecated": false, "digest": { "line_hashes": [ "296485909753592348215590702035423973730", "168870151593064014731992782391427668111", "190967533391762100296047511119884918694", "305734183601165156642472393042807156580", "323872210325311784680431332968123191995", "313972715112378856992143936745060230737", "193133904891312589228743778978961858447", "184927299036527615121285700409138451935", "188505058886581550624062103115505177042", "317861302494051890453606535245178224207", "190880779094411461120938330537060698748", "231919902297431052914146251260368951868", "47094099555610417519285860738891533573", "9192431344743619849023820040554908090", "255095236668510372343636010412503553765", "228629650719081065619324853137458336104", "286204902269261971518091630826564952999", "54258316318111234017000329040542654330", "302968128323629531079358534310626904704", "241347700797313431415036782978803120782", "272312178184303810642642164517396017842", "151857170148406037400288183407776186752", "206271085107374343257231836085817140430", "5232601418819513270062322455642124182", "300612717105267491561522875306362084842", "172323547174712419865065231350217730156", "339382015342740949587980342968302258401", "86843803705924374476335200030445445761" ], "threshold": 0.9 }, "id": "CVE-2024-26944-bf216758", "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@34ca809e055eca5cfe63d9c7efbf80b7c21b4e57" }, { "signature_version": "v1", "signature_type": "Function", "target": { "file": "fs/btrfs/zoned.c", "function": "do_zone_finish" }, "deprecated": false, "digest": { "length": 2461.0, "function_hash": "167769436227192270313270889154492827608" }, "id": "CVE-2024-26944-fbe5b649", "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@34ca809e055eca5cfe63d9c7efbf80b7c21b4e57" } ] }