{"cve":"CVE-2026-98080","nvd":{"published":"2026-09-25T11:17:37.417","modified":"2026-10-19T10:18:03.930","status":"Analyzed","description":"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---","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-672"],"references":["https://git.kernel.org/stable/c/203cbfb4fba590bd9b08bd36fa6d05b5d28923bf","https://git.kernel.org/stable/c/21bd77c132f18dc21c6fcdf417310d1adcf7448b","https://git.kernel.org/stable/c/7caaae233a55e167063f4cfa3385b1a04c8bbecb","https://git.kernel.org/stable/c/7ce02d52548b672795511c2cac8da6ec79ac8877","https://git.kernel.org/stable/c/b5d5ab5a715001dd937c920ef8c5688fd4999ba1"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-98080","score":0.00132,"percentile":0.02745,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}