FKIE_CVE-2026-90139

Vulnerability from fkie_nvd - Published: 2026-09-17 17:17 - Updated: 2026-09-17 17:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: fuse: check for NULL root inode in fuse_fill_super_submount fuse_iget() can return NULL when its inode allocation fails, but fuse_fill_super_submount() passed the result straight to get_fuse_inode() and decremented fi->nlookup without checking it: root = fuse_iget(sb, parent_fi->nodeid, ...); fi = get_fuse_inode(root); fi->nlookup--; Inside fuse_iget() the inode allocation can fail and return NULL. The submount root takes the iget5_locked() path, whose alloc_inode() can fail under memory pressure (the auto-submount branch can fail the same way in new_inode() or fuse_alloc_submount_lookup()): inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid); if (!inode) return NULL; A NULL root makes get_fuse_inode() a container_of() on NULL and the nlookup decrement a write to a bogus address, oopsing the mount. With CONFIG_KASAN the following null pointer dereference is reported when the root inode allocation of an auto-submount fails (e.g. under memory pressure): ================================================================== BUG: KASAN: null-ptr-deref in fuse_get_tree_submount+0x656/0x8b0 Read of size 8 at addr 00000000000002b0 by task ls/942 CPU: 0 PID: 942 Comm: ls Tainted: G W 6.6 #15 Call Trace: <TASK> fuse_get_tree_submount+0x656/0x8b0 vfs_get_tree+0x48/0x140 fc_mount+0x13/0x50 fuse_dentry_automount+0x7a/0xb0 __traverse_mounts+0xca/0x330 step_into+0x339/0xac0 path_lookupat+0xc5/0x2f0 filename_lookup+0x163/0x2a0 vfs_statx+0xd5/0x200 do_statx+0x83/0xd0 __x64_sys_statx+0xa0/0xc0 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x78/0xe2 </TASK> ================================================================== Return -ENOMEM instead; the caller tears down the partially built superblock on error, matching the other error returns in this function.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/17120c5bfb16808509ea18d7fab6027802d93eba
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/509f4a09bae7f03c87f67f053648874a5e177867
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/928f659a3e3650978a5b4829cc982324f72b474b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a5129155ca9fba40d77ff19ffead8244e88d6f9c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e0b7f2922f6bd4c23cbddb7d1fc2bada570d27d1
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/fuse/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "17120c5bfb16808509ea18d7fab6027802d93eba",
              "status": "affected",
              "version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
              "versionType": "git"
            },
            {
              "lessThan": "e0b7f2922f6bd4c23cbddb7d1fc2bada570d27d1",
              "status": "affected",
              "version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
              "versionType": "git"
            },
            {
              "lessThan": "a5129155ca9fba40d77ff19ffead8244e88d6f9c",
              "status": "affected",
              "version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
              "versionType": "git"
            },
            {
              "lessThan": "509f4a09bae7f03c87f67f053648874a5e177867",
              "status": "affected",
              "version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
              "versionType": "git"
            },
            {
              "lessThan": "928f659a3e3650978a5b4829cc982324f72b474b",
              "status": "affected",
              "version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/fuse/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.10"
            },
            {
              "lessThan": "5.10",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfuse: check for NULL root inode in fuse_fill_super_submount\n\nfuse_iget() can return NULL when its inode allocation fails, but\nfuse_fill_super_submount() passed the result straight to get_fuse_inode()\nand decremented fi-\u003enlookup without checking it:\n\n        root = fuse_iget(sb, parent_fi-\u003enodeid, ...);\n        fi = get_fuse_inode(root);\n        fi-\u003enlookup--;\n\nInside fuse_iget() the inode allocation can fail and return NULL.  The\nsubmount root takes the iget5_locked() path, whose alloc_inode() can fail\nunder memory pressure (the auto-submount branch can fail the same way in\nnew_inode() or fuse_alloc_submount_lookup()):\n\n        inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set,\n                             \u0026nodeid);\n        if (!inode)\n                return NULL;\n\nA NULL root makes get_fuse_inode() a container_of() on NULL and the\nnlookup decrement a write to a bogus address, oopsing the mount.  With\nCONFIG_KASAN the following null pointer dereference is reported when the\nroot inode allocation of an auto-submount fails (e.g. under memory\npressure):\n\n==================================================================\nBUG: KASAN: null-ptr-deref in fuse_get_tree_submount+0x656/0x8b0\nRead of size 8 at addr 00000000000002b0 by task ls/942\nCPU: 0 PID: 942 Comm: ls Tainted: G W 6.6 #15\nCall Trace:\n \u003cTASK\u003e\n fuse_get_tree_submount+0x656/0x8b0\n vfs_get_tree+0x48/0x140\n fc_mount+0x13/0x50\n fuse_dentry_automount+0x7a/0xb0\n __traverse_mounts+0xca/0x330\n step_into+0x339/0xac0\n path_lookupat+0xc5/0x2f0\n filename_lookup+0x163/0x2a0\n vfs_statx+0xd5/0x200\n do_statx+0x83/0xd0\n __x64_sys_statx+0xa0/0xc0\n do_syscall_64+0x37/0x90\n entry_SYSCALL_64_after_hwframe+0x78/0xe2\n \u003c/TASK\u003e\n==================================================================\n\nReturn -ENOMEM instead; the caller tears down the partially built\nsuperblock on error, matching the other error returns in this\nfunction."
    }
  ],
  "id": "CVE-2026-90139",
  "lastModified": "2026-09-17T17:17:06.523",
  "metrics": {},
  "published": "2026-09-17T17:17:06.523",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/17120c5bfb16808509ea18d7fab6027802d93eba"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/509f4a09bae7f03c87f67f053648874a5e177867"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/928f659a3e3650978a5b4829cc982324f72b474b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a5129155ca9fba40d77ff19ffead8244e88d6f9c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e0b7f2922f6bd4c23cbddb7d1fc2bada570d27d1"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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