{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-93813","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-18T17:59:28.790Z","datePublished":"2026-09-24T16:02:49.907Z","dateUpdated":"2026-10-03T10:57:45.809Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-03T10:57:45.809Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: tree-checker: validate INODE_REF's namelen\n\n[BUG]\nA crafted btrfs image can trigger the following crash:\n\n  BUG: unable to handle page fault for address: ffffd1dc42884000\n  #PF: supervisor write access in kernel mode\n  #PF: error_code(0x0002) - not-present page\n  CPU: 9 UID: 0 PID: 1034 Comm: poc Not tainted 7.1.0-rc4-custom+ #383 PREEMPT(full)  46af0a92938a63be7132e0dfd71e62327c51d5c2\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022\n  RIP: 0010:memcpy+0xc/0x10\n  Call Trace:\n   <TASK>\n   read_extent_buffer+0xe4/0x100 [btrfs 3cf0785dd58fec8c5ff84633b772f17ce1f92a8f]\n   btrfs_get_name+0x15e/0x1e0 [btrfs 3cf0785dd58fec8c5ff84633b772f17ce1f92a8f]\n   reconnect_path+0x165/0x390\n   exportfs_decode_fh_raw+0x337/0x400\n   ? drop_caches_sysctl_handler+0xb0/0xb0\n   </TASK>\n  ---[ end trace 0000000000000000 ]---\n  RIP: 0010:memcpy+0xc/0x10\n  Kernel panic - not syncing: Fatal exception\n\n[CAUSE]\nTThe crafted image has the following corrupted INODE_REF item:\n\n         item 9 key (258 INODE_REF 257) itemoff 11544 itemsize 4106\n         \tindex 2 namelen 4096 name: d\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\\000\n\nThe itemsize matches the namelen, but the namelen is 4096, way larger\nthan normal name length limit (BTRFS_NAME_LEN, 255).\n\nMeanwhile the memory of the @name is only 255 byte sized, this will cause\nout-of-boundary access, and cause the above crash.\n\n[FIX]\nAdd extra namelen verification for INODE_REF, just like what we have\ndone in ROOT_REF checks.\n\nNow the crafted image can be rejected gracefully:\n\n BTRFS critical (device dm-2): corrupt leaf: root=5 block=30572544 slot=14 ino=259, invalid inode ref name length, has 4096 expect [1, 255]\n BTRFS error (device dm-2): read time tree block corruption detected on logical 30572544 mirror 2\n\n[ Rebase, add a Link: tag, add an simple cause analyze ]"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - check_inode_ref() failed to cap INODE_REF name_len, so a crafted leaf with name_len 4096 is accepted. Those bytes come from the mounted image, not a protocol field. The overflow is open_by_handle_at() → do_handle_to_path() → exportfs_decode_fh_raw() → reconnect_path() → btrfs_get_name(); btrfs_fid has only objectid/gen, so an NFS handle does not carry the bad namelen.\nAC:L - The attacker writes an INODE_REF whose name_len exceeds BTRFS_NAME_LEN (255) but fits the item (PoC: 4096/4106), which the old check_inode_ref() allowed. Mounting that image and calling open_by_handle_at() on a directory filehandle for that inode makes reconnect_path() call btrfs_get_name() every time; no race or uninducible device failure is required.\nPR:L - btrfs_fs_type lacks FS_USERNS_MOUNT, so mount_capable() needs init-ns CAP_SYS_ADMIN, but a local user can mount the image via udisks2/polkit. The trigger is open_by_handle_at(): may_decode_fh() admits ns_capable(current_user_ns(), CAP_DAC_READ_SEARCH) with capable_wrt_mount() and O_DIRECTORY, so userns root on that mount is enough.\nUI:N - The attacker authors the INODE_REF, mounts the image (udisks/loop), and calls open_by_handle_at() so reconnect_path() runs btrfs_get_name() on that inode. That is their own action against data they already control; no second user must open a file or confirm a dialog.\nS:U - btrfs_get_name()'s overflow of exportfs_decode_fh_raw()'s nbuf corrupts the host kernel stack only. It does not cross a KVM/Xen guest-host, IOMMU/DMA, or other security-authority boundary.\nC:H - read_extent_buffer() in btrfs_get_name() memcpy's the attacker-chosen INODE_REF name (PoC namelen 4096) into exportfs_decode_fh_raw()'s nbuf[NAME_MAX+1] (256 bytes). That stack overflow overwrites saved frames and is kernel memory corruption usable for arbitrary disclosure.\nI:H - The same unbounded copy, plus name[name_len]='\\0' at offset 4096, is an attacker-controlled out-of-bounds write into kernel stack in exportfs_decode_fh_raw(). Chosen namelen/name bytes enable return-address overwrite and control-flow hijack, not a bounded metadata tweak.\nA:H - The reporter's PoC faults in memcpy() from read_extent_buffer() called by btrfs_get_name() (supervisor write to an unmapped address) and panics. Any name_len that runs nbuf off the mapped stack oopses the host."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/tree-checker.c"],"versions":[{"version":"2ede0daf01549cecf4bb0962c46dc47382047523","lessThan":"60078a3e25c09d9d8fba828b0d81bb33e449a1b2","status":"affected","versionType":"git"},{"version":"2ede0daf01549cecf4bb0962c46dc47382047523","lessThan":"509d6a4d889e425f305461d8323a7b39ca6c121c","status":"affected","versionType":"git"},{"version":"2ede0daf01549cecf4bb0962c46dc47382047523","lessThan":"4cb41f07685f88ec724a375883bb0c731db8f6eb","status":"affected","versionType":"git"},{"version":"2ede0daf01549cecf4bb0962c46dc47382047523","lessThan":"eeddee090b834a7d4b6a8214d2e3739e64c7a338","status":"affected","versionType":"git"},{"version":"2ede0daf01549cecf4bb0962c46dc47382047523","lessThan":"8f75c19892263bc0555fba922aefe103e841e86d","status":"affected","versionType":"git"},{"version":"2ede0daf01549cecf4bb0962c46dc47382047523","lessThan":"3dc22abc21f5892406c09202fa2627196cc96967","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/tree-checker.c"],"versions":[{"version":"2.6.37","status":"affected"},{"version":"0","lessThan":"2.6.37","status":"unaffected","versionType":"semver"},{"version":"5.15.222","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.189","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.158","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.111","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.53","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/60078a3e25c09d9d8fba828b0d81bb33e449a1b2"},{"url":"https://git.kernel.org/stable/c/509d6a4d889e425f305461d8323a7b39ca6c121c"},{"url":"https://git.kernel.org/stable/c/4cb41f07685f88ec724a375883bb0c731db8f6eb"},{"url":"https://git.kernel.org/stable/c/eeddee090b834a7d4b6a8214d2e3739e64c7a338"},{"url":"https://git.kernel.org/stable/c/8f75c19892263bc0555fba922aefe103e841e86d"},{"url":"https://git.kernel.org/stable/c/3dc22abc21f5892406c09202fa2627196cc96967"}],"title":"btrfs: tree-checker: validate INODE_REF's namelen","x_generator":{"engine":"bippy-1.2.0"}}}}