CVE-2023-53247
📋 TL;DR
A race condition vulnerability in the Linux kernel's Btrfs filesystem can cause kernel panics during file expansion operations. This affects Linux systems using Btrfs with subpage support enabled, potentially leading to denial of service. The vulnerability occurs when the kernel incorrectly handles page mapping during read operations.
💻 Affected Systems
- Linux kernel
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, requiring physical or remote console access to reboot.
Likely Case
System crash during specific file operations (like copy_file_range) when using Btrfs with subpage blocksize configurations.
If Mitigated
No impact if Btrfs subpage support is disabled or if not using Btrfs filesystem.
🎯 Exploit Status
Requires specific Btrfs configuration and timing to trigger; discovered during filesystem testing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 0a5e0bc8e8618e32a6ca64450867628eb0a627bf, 17b17fcd6d446b95904a6929c40012ee7f0afc0c, a5880e69cf7fe4a0bb1eabae02205352d1b59b7b
Vendor Advisory: https://git.kernel.org/stable/c/0a5e0bc8e8618e32a6ca64450867628eb0a627bf
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix. 2. Check with your distribution for backported patches. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable Btrfs subpage support
LinuxPrevent the vulnerable code path by disabling subpage blocksize support in Btrfs
mount -o remount,nosubpage /mount/point
🧯 If You Can't Patch
- Avoid using Btrfs filesystem for critical systems
- Disable subpage support on existing Btrfs mounts
🔍 How to Verify
Check if Vulnerable:
Check kernel version and Btrfs mount options: uname -r and cat /proc/mounts | grep btrfsCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is patched and test with filesystem operations that previously triggered crashes📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages mentioning btrfs_subpage_assert
- System crash logs during file operations
Network Indicators:
- None - local filesystem issue
SIEM Query:
kernel: "btrfs_subpage_assert" OR "BUG at fs/btrfs/subpage.c"