Bug 2461550 (CVE-2026-31596)

Summary: CVE-2026-31596 kernel: ocfs2: handle invalid dinode in ocfs2_group_extend
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the OCFS2 (Oracle Cluster File System, version 2) component of the Linux kernel. A local attacker with control over a specially crafted filesystem could exploit a vulnerability in the `ocfs2_group_extend` function. This flaw arises from an insufficient validation of a global bitmap inode block, allowing a crafted filesystem to bypass structural validation. Successful exploitation leads to a kernel crash, resulting in a denial of service.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-04-24 15:07:57 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ocfs2: handle invalid dinode in ocfs2_group_extend

[BUG]
kernel BUG at fs/ocfs2/resize.c:308!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
RIP: 0010:ocfs2_group_extend+0x10aa/0x1ae0 fs/ocfs2/resize.c:308
Code: 8b8520ff ffff83f8 860f8580 030000e8 5cc3c1fe
Call Trace:
 ...
 ocfs2_ioctl+0x175/0x6e0 fs/ocfs2/ioctl.c:869
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x197/0x1e0 fs/ioctl.c:583
 x64_sys_call+0x1144/0x26a0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x93/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
 ...

[CAUSE]
ocfs2_group_extend() assumes that the global bitmap inode block
returned from ocfs2_inode_lock() has already been validated and
BUG_ONs 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 ocfs2_group_extend(). If the global
bitmap buffer does not contain a valid dinode, report filesystem
corruption with ocfs2_error() and fail the resize operation instead of
crashing the kernel.
Comment 1 Keith Grant 2026-04-24 19:10:49 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042416-CVE-2026-31596-0201@gregkh/T