CVE-2026-98080
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: do not force reloc root creation during qgroup_account_snapshot() [BUG] When running btrfs/252 with quota enabled through MKFS_OPTIONS="-O quota", it has a high chance to trigger the following kernel warning and flips the fs RO: BTRFS info (device dm-2): relocating block group 30408704 flags metadata|dup ------------[ cut here ]------------ WARNING: fs/btrfs/extent-tree.c:879 at lookup_inline_extent_backref+0x74b/0x960 [btrfs], CPU#4: btrfs/2173 CPU: 4 UID: 0 PID: 2173 Comm: btrfs Not tainted 7.2.0-rc6-custom+ #457 PREEMPT(full) 3adc6528fb66f7a55fe1095385818e742f200aab Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:lookup_inline_extent_backref+0x74b/0x960 [btrfs] Call Trace: <TASK> insert_inline_extent_backref+0x7c/0x160 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] __btrfs_inc_extent_ref+0xa9/0x270 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] __btrfs_run_delayed_refs+0x4af/0x11c0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] btrfs_run_delayed_refs+0x9d/0xf0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] create_pending_snapshot+0x39d/0xf00 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] create_pending_snapshots+0x9b/0xc0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] btrfs_commit_transaction+0x280/0xeb0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] prepare_to_relocate+0x147/0x200 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] relocate_block_group+0x6b/0x5e0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] btrfs_relocate_block_group+0x92c/0x2380 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] btrfs_relocate_chunk+0x3f/0x1a0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] btrfs_balance+0xa2c/0x19c0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] btrfs_ioctl+0x2839/0x2d30 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72] __x64_sys_ioctl+0x416/0x9a0 do_syscall_64+0xe1/0x790 entry_SYSCALL_64_after_hwframe+0x4b/0x53 </TASK> ---[ end trace 0000000000000000 ]--- BTRFS info (device dm-2): leaf 4593991680 gen 233 total ptrs 175 free space 5953 owner 2 BTRFS info (device dm-2): refs 3 lock_owner 2173 current 2173 item 0 key (166772736 METADATA_ITEM 1) itemoff 16250 itemsize 33 extent refs 1 gen 222 flags 2 ref#0: tree block backref root 266 [ Skip the tree dump ] item 174 key (263225344 METADATA_ITEM 0) itemoff 10328 itemsize 33 extent refs 1 gen 162 flags 258 ref#0: tree block backref root 267 BTRFS error (device dm-2): extent item not found for insert, bytenr 179847168 num_bytes 16384 parent 4594335744 root_objectid 273 owner 0 offset 0 BTRFS error (device dm-2): failed to run delayed ref for logical 179847168 num_bytes 16384 type 182 action 1 ref_mod 1: -117 [CAUSE] The above error is showing that there is a tree reference to a metadata extent that is no longer there. With "ref_verify" mount option (requires CONFIG_BTRFS_DEBUG), there is some extra debug output: BTRFS error (device dm-2): dumping block entry [180961280 16384], num_refs 0, metadata 1, from disk 0 BTRFS error (device dm-2): root entry 256, num_refs 18446744073709551615 BTRFS error (device dm-2): root entry 273, num_refs 18446744073709551615 BTRFS error (device dm-2): Ref action 3, root 273, ref_root 273, parent 0, owner 0, offset 0, num_refs 1 btrfs_force_cow_block+0x129/0x7d0 [btrfs] btrfs_cow_block+0x10a/0x250 [btrfs] btrfs_search_slot+0x5eb/0xf40 [btrfs] btrfs_insert_empty_items+0x3a/0x70 [btrfs] insert_with_overflow+0x53/0x130 [btrfs] btrfs_insert_dir_item+0x125/0x290 [btrfs] btrfs_add_link+0xaa/0x410 [btrfs] btrfs_rename+0x5ea/0xcd0 [btrfs] btrfs_rename2+0x28/0x60 [btrfs] vfs_rename+0x5b2/0xe10 filename_renameat2+0x244/0x430 __x64_sys_rename+0x48/0x70 do_syscall_64+0xe1/0x790 entry_SYSCALL_64_after_hwframe+0x4b/0x53 ---truncated---
View original CVE JSON
{
"id": "CVE-2026-98080",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-25T11:17:37.417",
"lastModified": "2026-10-19T10:18:03.930",
"vulnStatus": "Analyzed",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not force reloc root creation during qgroup_account_snapshot()\n\n[BUG]\nWhen running btrfs/252 with quota enabled through MKFS_OPTIONS=\"-O quota\",\nit has a high chance to trigger the following kernel warning and flips\nthe fs RO:\n\n BTRFS info (device dm-2): relocating block group 30408704 flags metadata|dup\n ------------[ cut here ]------------\n WARNING: fs/btrfs/extent-tree.c:879 at lookup_inline_extent_backref+0x74b/0x960 [btrfs], CPU#4: btrfs/2173\n CPU: 4 UID: 0 PID: 2173 Comm: btrfs Not tainted 7.2.0-rc6-custom+ #457 PREEMPT(full) 3adc6528fb66f7a55fe1095385818e742f200aab\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022\n RIP: 0010:lookup_inline_extent_backref+0x74b/0x960 [btrfs]\n Call Trace:\n <TASK>\n insert_inline_extent_backref+0x7c/0x160 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n __btrfs_inc_extent_ref+0xa9/0x270 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n __btrfs_run_delayed_refs+0x4af/0x11c0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n btrfs_run_delayed_refs+0x9d/0xf0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n create_pending_snapshot+0x39d/0xf00 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n create_pending_snapshots+0x9b/0xc0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n btrfs_commit_transaction+0x280/0xeb0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n prepare_to_relocate+0x147/0x200 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n relocate_block_group+0x6b/0x5e0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n btrfs_relocate_block_group+0x92c/0x2380 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n btrfs_relocate_chunk+0x3f/0x1a0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n btrfs_balance+0xa2c/0x19c0 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n btrfs_ioctl+0x2839/0x2d30 [btrfs 32f09462c54d9c922fca74a3e4866f4aa7737b72]\n __x64_sys_ioctl+0x416/0x9a0\n do_syscall_64+0xe1/0x790\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n </TASK>\n ---[ end trace 0000000000000000 ]---\n BTRFS info (device dm-2): leaf 4593991680 gen 233 total ptrs 175 free space 5953 owner 2\n BTRFS info (device dm-2): refs 3 lock_owner 2173 current 2173\n \titem 0 key (166772736 METADATA_ITEM 1) itemoff 16250 itemsize 33\n \t\textent refs 1 gen 222 flags 2\n \t\tref#0: tree block backref root 266\n [ Skip the tree dump ]\n \titem 174 key (263225344 METADATA_ITEM 0) itemoff 10328 itemsize 33\n \t\textent refs 1 gen 162 flags 258\n \t\tref#0: tree block backref root 267\n BTRFS error (device dm-2): extent item not found for insert, bytenr 179847168 num_bytes 16384 parent 4594335744 root_objectid 273 owner 0 offset 0\n BTRFS error (device dm-2): failed to run delayed ref for logical 179847168 num_bytes 16384 type 182 action 1 ref_mod 1: -117\n\n[CAUSE]\nThe above error is showing that there is a tree reference to a metadata\nextent that is no longer there.\n\nWith \"ref_verify\" mount option (requires CONFIG_BTRFS_DEBUG), there is\nsome extra debug output:\n\n BTRFS error (device dm-2): dumping block entry [180961280 16384], num_refs 0, metadata 1, from disk 0\n BTRFS error (device dm-2): root entry 256, num_refs 18446744073709551615\n BTRFS error (device dm-2): root entry 273, num_refs 18446744073709551615\n BTRFS error (device dm-2): Ref action 3, root 273, ref_root 273, parent 0, owner 0, offset 0, num_refs 1\n btrfs_force_cow_block+0x129/0x7d0 [btrfs]\n btrfs_cow_block+0x10a/0x250 [btrfs]\n btrfs_search_slot+0x5eb/0xf40 [btrfs]\n btrfs_insert_empty_items+0x3a/0x70 [btrfs]\n insert_with_overflow+0x53/0x130 [btrfs]\n btrfs_insert_dir_item+0x125/0x290 [btrfs]\n btrfs_add_link+0xaa/0x410 [btrfs]\n btrfs_rename+0x5ea/0xcd0 [btrfs]\n btrfs_rename2+0x28/0x60 [btrfs]\n vfs_rename+0x5b2/0xe10\n filename_renameat2+0x244/0x430\n __x64_sys_rename+0x48/0x70\n do_syscall_64+0xe1/0x790\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n \n---truncated---"
}
],
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],
"metrics": {
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{
"source": "[email protected]",
"type": "Primary",
"cvssData": {
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6
}
]
},
"weaknesses": [
{
"source": "[email protected]",
"type": "Primary",
"description": [
{
"lang": "en",
"value": "CWE-672"
}
]
}
],
"configurations": [
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