{"id":"CVE-2025-38172","state":"PUBLISHED","title":"erofs: avoid using multiple devices with different type","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: avoid using multiple devices with different type\n\nFor multiple devices, both primary and extra devices should be the\nsame type. `erofs_init_device` has already guaranteed that if the\nprimary is a file-backed device, extra devices should also be\nregular files.\n\nHowever, if the primary is a block device while the extra device\nis a file-backed device, `erofs_init_device` will get an ENOTBLK,\nwhich is not treated as an error in `erofs_fc_get_tree`, and that\nleads to an UAF:\n\n  erofs_fc_get_tree\n    get_tree_bdev_flags(erofs_fc_fill_super)\n      erofs_read_superblock\n        erofs_init_device  // sbi->dif0 is not inited yet,\n                           // return -ENOTBLK\n      deactivate_locked_super\n        free(sbi)\n    if (err is -ENOTBLK)\n      sbi->dif0.file = filp_open()  // sbi UAF\n\nSo if -ENOTBLK is hitted in `erofs_init_device`, it means the\nprimary device must be a block device, and the extra device\nis not a block device. The error can be converted to -EINVAL.","publishedAt":"2025-07-03T08:36:10.334Z","updatedAt":"2026-08-05T12:00:03.095Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fb176750266a3d7f42ebdcf28e8ba40350b27847","status":"affected","lessThan":"65115472f741ca000d7ea4a5922214f93cd1516e","versionType":"git"},{"version":"fb176750266a3d7f42ebdcf28e8ba40350b27847","status":"affected","lessThan":"cd04beb9ce2773a16057248bb4fa424068ae3807","versionType":"git"},{"version":"fb176750266a3d7f42ebdcf28e8ba40350b27847","status":"affected","lessThan":"9748f2f54f66743ac77275c34886a9f890e18409","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/erofs/super.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.34","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.15.3","status":"unaffected","lessThanOrEqual":"6.15.*","versionType":"semver"},{"version":"6.16","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/erofs/super.c"]}],"references":["https://git.kernel.org/stable/c/65115472f741ca000d7ea4a5922214f93cd1516e","https://git.kernel.org/stable/c/cd04beb9ce2773a16057248bb4fa424068ae3807","https://git.kernel.org/stable/c/9748f2f54f66743ac77275c34886a9f890e18409"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/38xxx/CVE-2025-38172.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-38172","state":"PUBLISHED","datePublished":"2025-07-03T08:36:10.334Z","dateUpdated":"2026-08-05T12:00:03.095Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T04:51:23.991Z"},"containers":{"cna":{"title":"erofs: avoid using multiple devices with different type","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: avoid using multiple devices with different type\n\nFor multiple devices, both primary and extra devices should be the\nsame type. `erofs_init_device` has already guaranteed that if the\nprimary is a file-backed device, extra devices should also be\nregular files.\n\nHowever, if the primary is a block device while the extra device\nis a file-backed device, `erofs_init_device` will get an ENOTBLK,\nwhich is not treated as an error in `erofs_fc_get_tree`, and that\nleads to an UAF:\n\n  erofs_fc_get_tree\n    get_tree_bdev_flags(erofs_fc_fill_super)\n      erofs_read_superblock\n        erofs_init_device  // sbi->dif0 is not inited yet,\n                           // return -ENOTBLK\n      deactivate_locked_super\n        free(sbi)\n    if (err is -ENOTBLK)\n      sbi->dif0.file = filp_open()  // sbi UAF\n\nSo if -ENOTBLK is hitted in `erofs_init_device`, it means the\nprimary device must be a block device, and the extra device\nis not a block device. The error can be converted to -EINVAL."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fb176750266a3d7f42ebdcf28e8ba40350b27847","status":"affected","lessThan":"65115472f741ca000d7ea4a5922214f93cd1516e","versionType":"git"},{"version":"fb176750266a3d7f42ebdcf28e8ba40350b27847","status":"affected","lessThan":"cd04beb9ce2773a16057248bb4fa424068ae3807","versionType":"git"},{"version":"fb176750266a3d7f42ebdcf28e8ba40350b27847","status":"affected","lessThan":"9748f2f54f66743ac77275c34886a9f890e18409","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/erofs/super.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.34","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.15.3","status":"unaffected","lessThanOrEqual":"6.15.*","versionType":"semver"},{"version":"6.16","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/erofs/super.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/65115472f741ca000d7ea4a5922214f93cd1516e"},{"url":"https://git.kernel.org/stable/c/cd04beb9ce2773a16057248bb4fa424068ae3807"},{"url":"https://git.kernel.org/stable/c/9748f2f54f66743ac77275c34886a9f890e18409"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerability is reached only through the local mount(2)/fsconfig(2)+fsmount(2) filesystem-mount path on an erofs image plus its `device=` parameters; there is no network-facing consumer of this code.\nAC:L - The trigger is fully deterministic — an erofs image whose on-disk device table count matches the supplied `device=` options, with one such path naming a regular file instead of a block device, reliably yields -ENOTBLK and the use-after-free write on every attempt. Heap reuse of the freed `erofs_sb_info` is attacker-assisted because the free→write window spans an attacker-influenceable `filp_open()` path walk that can be stalled arbitrarily, and the spray runs from the attacker's own threads.\nPR:N - The attacker needs no account or capability on the target: they only supply the malicious erofs image and/or arrange the `device=` path (which is resolved with symlink following at fill_super time, in directories such as container blob/staging dirs) to be a non-block file, while a privileged mounter — automounter, container/composefs runtime, or mount helper handling multi-device erofs images — performs the mount. This matches the kernel CNA treatment of crafted-image mount bugs (e.g. CVE-2025-38204, CVE-2025-38230, CVE-2025-38652).\nUI:R - The flaw only fires when someone mounts the attacker-supplied erofs image with the corresponding `device=` parameters; it cannot be triggered without that mount action.\nS:U - The freed object, the corrupted slab memory, and the resulting crash or escalation are all inside the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - `file_inode(sbi->dif0.file)->i_mode` is read back out of the freed `erofs_sb_info`; if a sprayed object has taken the slot the kernel dereferences an attacker-groomed pointer and reads memory at an attacker-chosen location, and use-after-free of a kmalloc object is generally leverageable into kernel-memory disclosure.\nI:H - `sbi->dif0.file = file` writes a valid kernel `struct file *` at a fixed offset (16) into a freed generic-kmalloc chunk, clobbering whatever live object has been reallocated there — a classic UAF write primitive that overwrites pointers/state of an unrelated kernel object and is a strong stepping stone to control-flow hijacking.\nA:H - Even without grooming, the UAF read of poisoned/reused memory and the follow-on `get_tree_nodev()` path (which calls `erofs_fc_fill_super()` with `s_fs_info == NULL`, immediately writing through a NULL `sbi`) produce a kernel oops/panic, and the path also leaks a `struct file` reference on every attempt."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:00:03.095Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.12.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.15.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.16"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}