CVE-2026-31596: ocfs2: handle invalid dinode in ocfs2_group_extend
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: handle invalid dinode in ocfs2groupextend
[BUG] kernel BUG at fs/ocfs2/resize.c:308! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:ocfs2groupextend+0x10aa/0x1ae0 fs/ocfs2/resize.c:308 Code: 8b8520ff ffff83f8 860f8580 030000e8 5cc3c1fe Call Trace: ... ocfs2ioctl+0x175/0x6e0 fs/ocfs2/ioctl.c:869 vfsioctl fs/ioctl.c:51 [inline] dosysioctl fs/ioctl.c:597 [inline] sesysioctl fs/ioctl.c:583 [inline] x64sysioctl+0x197/0x1e0 fs/ioctl.c:583 x64syscall+0x1144/0x26a0 arch/x86/include/generated/asm/syscalls64.h:17 dosyscallx64 arch/x86/entry/syscall64.c:63 [inline] dosyscall64+0x93/0xf80 arch/x86/entry/syscall64.c:94 entrySYSCALL64afterhwframe+0x76/0x7e ...
[CAUSE] ocfs2groupextend() assumes that the global bitmap inode block returned from ocfs2inodelock() has already been validated and BUGONs when the signature is not a dinode. That assumption is too strong for crafted filesystems because the JBD2-managed buffer path can bypass structural validation and return an invalid dinode to the resize ioctl.
[FIX] Validate the dinode explicitly in ocfs2groupextend(). If the global bitmap buffer does not contain a valid dinode, report filesystem corruption with ocfs2error() and fail the resize operation instead of crashing the kernel.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Avoid performing OCFS2 resize operations (the resize ioctl) and avoid mounting untrusted or crafted OCFS2 filesystems until a Linux kernel update containing the fix for ocfs2_group_extend's dinode validation is applied; restrict access to systems performing OCFS2 resize operations to trusted administrators only.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-31596?
The severity of CVE-2026-31596 is classified as high due to the potential for a kernel panic leading to system instability.
How do I fix CVE-2026-31596?
To fix CVE-2026-31596, update to the latest patched version of the Linux kernel that addresses this vulnerability.
What systems are affected by CVE-2026-31596?
CVE-2026-31596 affects systems running the OCFS2 filesystem within the Linux kernel.
What are the potential impacts of CVE-2026-31596?
The potential impacts of CVE-2026-31596 include system crashes and data corruption due to handling invalid dinodes.
Is there a workaround for CVE-2026-31596?
There is no known workaround for CVE-2026-31596; the best action is to apply the security update as soon as available.