Linux Kernel up to 6.9.8 btrfs_qgroup_inherit out-of-bounds

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Linux Kernel up to 6.9.8. Affected by this issue is the function btrfs_qgroup_inherit. This manipulation causes out-of-bounds. This vulnerability appears as CVE-2024-42111. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Linux Kernel up to 6.9.8. Affected by this vulnerability is the function btrfs_qgroup_inherit. The manipulation with an unknown input leads to a out-of-bounds vulnerability. The CWE definition for the vulnerability is CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: btrfs: always do the basic checks for btrfs_qgroup_inherit structure [BUG] Syzbot reports the following regression detected by KASAN: BUG: KASAN: slab-out-of-bounds in btrfs_qgroup_inherit+0x42e/0x2e20 fs/btrfs/qgroup.c:3277 Read of size 8 at addr ffff88814628ca50 by task syz-executor318/5171 CPU: 0 PID: 5171 Comm: syz-executor318 Not tainted 6.10.0-rc2-syzkaller-00010-g2ab795141095 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 btrfs_qgroup_inherit+0x42e/0x2e20 fs/btrfs/qgroup.c:3277 create_pending_snapshot+0x1359/0x29b0 fs/btrfs/transaction.c:1854 create_pending_snapshots+0x195/0x1d0 fs/btrfs/transaction.c:1922 btrfs_commit_transaction+0xf20/0x3740 fs/btrfs/transaction.c:2382 create_snapshot+0x6a1/0x9e0 fs/btrfs/ioctl.c:875 btrfs_mksubvol+0x58f/0x710 fs/btrfs/ioctl.c:1029 btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1075 __btrfs_ioctl_snap_create+0x387/0x4b0 fs/btrfs/ioctl.c:1340 btrfs_ioctl_snap_create_v2+0x1f2/0x3a0 fs/btrfs/ioctl.c:1422 btrfs_ioctl+0x99e/0xc60 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fcbf1992509 RSP: 002b:00007fcbf1928218 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fcbf1a1f618 RCX: 00007fcbf1992509 RDX: 0000000020000280 RSI: 0000000050009417 RDI: 0000000000000003 RBP: 00007fcbf1a1f610 R08: 00007ffea1298e97 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fcbf19eb660 R13: 00000000200002b8 R14: 00007fcbf19e60c0 R15: 0030656c69662f2e And it also pinned it down to commit b5357cb268c4 ("btrfs: qgroup: do not check qgroup inherit if qgroup is disabled"). [CAUSE] That offending commit skips the whole qgroup inherit check if qgroup is not enabled. But that also skips the very basic checks like num_ref_copies/num_excl_copies and the structure size checks. Meaning if a qgroup enable/disable race is happening at the background, and we pass a btrfs_qgroup_inherit structure when the qgroup is disabled, the check would be completely skipped. Then at the time of transaction commitment, qgroup is re-enabled and btrfs_qgroup_inherit() is going to use the incorrect structure and causing the above KASAN error. [FIX] Make btrfs_qgroup_check_inherit() only skip the source qgroup checks. So that even if invalid btrfs_qgroup_inherit structure is passed in, we can still reject invalid ones no matter if qgroup is enabled or not. Furthermore we do already have an extra safety inside btrfs_qgroup_inherit(), which would just ignore invalid qgroup sources, so even if we only skip the qgroup source check we're still safe.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2024-42111 since 07/29/2024. The exploitation appears to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 210060 (Ubuntu 22.04 LTS / 24.04 LTS : Linux kernel kernel vulnerabilities (USN-7089-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.9.9 eliminates this vulnerability. Applying the patch ebe5ea02577b/724d8042cef8 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (210060) and CERT Bund (WID-SEC-2024-1722). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• IBM InfoSphere Guardium
• Oracle Linux
• NetApp FAS
• NetApp ActiveIQ Unified Manager
• Siemens SIMATIC S7
• Oracle VM
• IBM Security Guardium
• RESF Rocky Linux
• Broadcom Brocade SANnav
• Dell PowerScale
• Open Source Linux Kernel
• IBM QRadar SIEM
• Dell integrated Dell Remote Access Controller
• IBM Storage Scale
• IBM Spectrum Protect Plus
• Juniper Junos Space
• IBM Storage Scale System
• SolarWinds Security Event Manager

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.9.0
• 6.9.1
• 6.9.2
• 6.9.3
• 6.9.4
• 6.9.5
• 6.9.6
• 6.9.7
• 6.9.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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