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CVE-2026-74359

configfs_lookup(): don't leave ->s_dentry dangling on failure

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, and 1 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

In the Linux kernel, the following vulnerability has been resolved: configfs_lookup(): don't leave ->s_dentry dangling on failure Normally ->s_dentry is cleared when dentry it's pointing to becomes negative (on eviction, realistically). However, that only happens if dentry gets to be positive in the first place; in case of inode allocation failure dentry never becomes positive, so ->d_iput() is not called at all. We do part of what normally would've been done by configfs_d_iput() (dropping the reference to configfs_dirent) manually, but we do not clear ->s_dentry there. Sloppy as it is, it does not matter in case of configfs_create_{dir,link}() - there configfs_dirent does not survive dropping the sole reference to it. However, for configfs_lookup() it does survive, with a dangling pointer to soon to be freed dentry sitting it its ->s_dentry. Subsequent getdents(2) in that directory will end up dereferencing that pointer in order to pick the inode number. Use after free... This is the minimal fix; the right approach is to set the linkage between dentry and configfs_dirent only after we know that we have an inode, but that takes more surgery and the bug had been there since 2006, so...

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 3d0f89bb169482d26d5aa4e82e763077e7e9bc4d · fixed in 3e83b2203aa59bd279e4f677ec793d49dc9d019e; From 3d0f89bb169482d26d5aa4e82e763077e7e9bc4d · fixed in b6e9c82522ddaa3ac0706b295ff4a71975d4f883; From 3d0f89bb169482d26d5aa4e82e763077e7e9bc4d · fixed in eee07d769da5ac4e4f7bd0bc17828646a318d499; From 3d0f89bb169482d26d5aa4e82e763077e7e9bc4d · fixed in 9c747dcee164ead300de90550ad9e4122f0d1bbb; From 3d0f89bb169482d26d5aa4e82e763077e7e9bc4d · fixed in c3b073a209a9baa691b744318ac929fecdd8847c; From 3d0f89bb169482d26d5aa4e82e763077e7e9bc4d · fixed in 57088b06109f3222963c639d8d743f42c2899b13; From 3d0f89bb169482d26d5aa4e82e763077e7e9bc4d · fixed in 10da12d352b7b2bb330a8609fdda9a58bf0e9856

  • Linux Linux

    2.6.16

  • KernelLinux

    From 2.6.16 · fixed in 5.15.212; From 5.16.0 · fixed in 6.1.178; From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.5

References 7

git.kernel.org