CVE-2024-39276

Summary

In the Linux kernel, the following vulnerability has been resolved:

ext4: fix mb_cache_entry's e_refcnt leak in ext4_xattr_block_cache_find()

Syzbot reports a warning as follows:

============================================ WARNING: CPU: 0 PID: 5075 at fs/mbcache.c:419 mb_cache_destroy+0x224/0x290 Modules linked in: CPU: 0 PID: 5075 Comm: syz-executor199 Not tainted 6.9.0-rc6-gb947cc5bf6d7 RIP: 0010:mb_cache_destroy+0x224/0x290 fs/mbcache.c:419 Call Trace: <TASK> ext4_put_super+0x6d4/0xcd0 fs/ext4/super.c:1375 generic_shutdown_super+0x136/0x2d0 fs/super.c:641 kill_block_super+0x44/0x90 fs/super.c:1675 ext4_kill_sb+0x68/0xa0 fs/ext4/super.c:7327 […]

This is because when finding an entry in ext4_xattr_block_cache_find(), if ext4_sb_bread() returns -ENOMEM, the ce's e_refcnt, which has already grown in the __entry_find(), won't be put away, and eventually trigger the above issue in mb_cache_destroy() due to reference count leakage.

So call mb_cache_entry_put() on the -ENOMEM error branch as a quick fix.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxb878c8a7f08f0c225b6a46ba1ac867e9c5d17807 < 9ad75e78747b5a50dc5a52f0f8e92e920a653f16affected
LinuxLinuxfb265c9cb49e2074ddcdd4de99728aefdd3b3592 < 896a7e7d0d555ad8b2b46af0c2fa7de7467f9483affected
LinuxLinuxfb265c9cb49e2074ddcdd4de99728aefdd3b3592 < 76dc776153a47372719d664e0fc50d6355791abbaffected
LinuxLinuxfb265c9cb49e2074ddcdd4de99728aefdd3b3592 < 681ff9a09accd8a4379f8bd30b7a1641ee19bb3eaffected
LinuxLinuxfb265c9cb49e2074ddcdd4de99728aefdd3b3592 < e941b712e758f615d311946bf98216e79145ccd9affected
LinuxLinuxfb265c9cb49e2074ddcdd4de99728aefdd3b3592 < a95df6f04f2c37291adf26a74205cde0314d4577affected
LinuxLinuxfb265c9cb49e2074ddcdd4de99728aefdd3b3592 < b37c0edef4e66fb21a2fbc211471195a383e5ab8affected
LinuxLinuxfb265c9cb49e2074ddcdd4de99728aefdd3b3592 < 0c0b4a49d3e7f49690a6827a41faeffad5df7e21affected
LinuxLinux9da1f6d06b7a6d068e68fcfd7cbbf6b586d888e1affected
LinuxLinux81313ed2c705d958744882a269bf4a5e3ddec95eaffected
LinuxLinux4.19.14 < 4.19.316affected
LinuxLinux4.14.92 < 4.15affected
LinuxLinux4.20.1 < 4.21affected
LinuxLinux5.0affected
LinuxLinux0 < 5.0unaffected
LinuxLinux4.19.316 <= 4.19.*unaffected
LinuxLinux5.4.278 <= 5.4.*unaffected
LinuxLinux5.10.219 <= 5.10.*unaffected
LinuxLinux5.15.161 <= 5.15.*unaffected
LinuxLinux6.1.94 <= 6.1.*unaffected
LinuxLinux6.6.34 <= 6.6.*unaffected
LinuxLinux6.9.5 <= 6.9.*unaffected
LinuxLinux6.10 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

CVE Program Container

Additional References

References