{"id":"CVE-2026-72193","summary":"ntfs3: cap RESTART_TABLE free-chain walker at rt-\u003eused","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nntfs3: cap RESTART_TABLE free-chain walker at rt-\u003eused\n\nA crafted NTFS3 disk image triggers an in-kernel infinite loop at\nmount time, hanging the mounting thread and firing the soft-lockup\nwatchdog within ~22s on multi-CPU hosts (panic with\nkernel.softlockup_panic=1).  The bug is reachable from desktop USB\nauto-mount on distributions where udisks2 routes the NTFS signature\nto the in-tree ntfs3 driver (Arch family and an increasing fraction\nof Fedora / openSUSE / RHEL deployments); CAP_SYS_ADMIN-class manual\nmount elsewhere.\n\ncheck_rstbl()'s second walker iterates the free-entry singly-linked\nlist headed by rt-\u003efirst_free with no upper bound on iteration count:\n\n  for (off = ff; off;) {\n      if (off == RESTART_ENTRY_ALLOCATED)\n          return false;\n      off = le32_to_cpu(*(__le32 *)Add2Ptr(rt, off));\n      if (off \u003e ts - sizeof(__le32))\n          return false;\n  }\n\nThe existing guards cover three exits: end-of-list (off == 0), the\nin-use marker (off == RESTART_ENTRY_ALLOCATED), and out-of-bounds\n(off \u003e ts - sizeof(__le32)).  None of the three prevents an\nin-bounds cycle.\n\nA crafted on-disk RESTART_TABLE whose free chain contains a\nself-loop or A-\u003eB-\u003eA cycle whose offsets satisfy:\n\n  - in range [sizeof(struct RESTART_TABLE), ts - sizeof(__le32)]\n  - (off - sizeof(struct RESTART_TABLE)) % rsize == 0\n\npasses all existing guards and spins the mount-time thread forever.\nReproduced in UML by hand-forging a 2 MB NTFS3 image whose journal\nRESTART_TABLE first_free = 0x18 and whose entry at offset 0x18\nstores 0x18 as its next pointer; mount of the forged image with\nthe in-tree ntfs3 driver never returns.\n\nBound the walker by rt-\u003eused.  Each entry on a legitimate free\nchain is unique, and the total slot count is ne = le16_to_cpu\n(rt-\u003eused).  A traversal that visits more than ne slots is by\nconstruction malformed; reject it as a corrupt RESTART_TABLE.\n\nAfter this patch, mount of the forged image returns with -EINVAL\nand a log_replay failure message, and mkntfs-produced legitimate\nimages mount cleanly (verified in the same UML harness).","modified":"2026-08-18T03:31:14.944239114Z","published":"2026-08-15T05:53:53.381Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72193.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0fad25687d4d3fa1fdd313d31b9cb5817c425029"},{"type":"WEB","url":"https://git.kernel.org/stable/c/29b86dbe88cbbef53bb9aaec2e279359f8c450f8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7972df425687daa70d971fe6ed415e78683133dd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7ac4c86915c24c208a0f0611b71d9676686fe756"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8128bec895075253c779d67afdc90ae513265fca"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9611f644302c07d21bc8af97e3e06a3d30064253"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d313416280d41bea272f02a6034dfa88008692a0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72193.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72193"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"b46acd6a6a627d876898e1c84d3f84902264b445"},{"fixed":"8128bec895075253c779d67afdc90ae513265fca"},{"fixed":"7972df425687daa70d971fe6ed415e78683133dd"},{"fixed":"7ac4c86915c24c208a0f0611b71d9676686fe756"},{"fixed":"29b86dbe88cbbef53bb9aaec2e279359f8c450f8"},{"fixed":"0fad25687d4d3fa1fdd313d31b9cb5817c425029"},{"fixed":"d313416280d41bea272f02a6034dfa88008692a0"},{"fixed":"9611f644302c07d21bc8af97e3e06a3d30064253"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72193.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.15.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72193.json"}}],"schema_version":"1.9.0"}