CVE-2023-54180
Unknown Unknown - Not Provided
Kernel BUG Trigger in Btrfs Dev-Replace Repair Causes System Crash

Publication date: 2025-12-30

Last updated on: 2025-12-30

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: handle case when repair happens with dev-replace [BUG] There is a bug report that a BUG_ON() in btrfs_repair_io_failure() (originally repair_io_failure() in v6.0 kernel) got triggered when replacing a unreliable disk: BTRFS warning (device sda1): csum failed root 257 ino 2397453 off 39624704 csum 0xb0d18c75 expected csum 0x4dae9c5e mirror 3 kernel BUG at fs/btrfs/extent_io.c:2380! invalid opcode: 0000 [#1] PREEMPT SMP NOPTI CPU: 9 PID: 3614331 Comm: kworker/u257:2 Tainted: G OE 6.0.0-5-amd64 #1 Debian 6.0.10-2 Hardware name: Micro-Star International Co., Ltd. MS-7C60/TRX40 PRO WIFI (MS-7C60), BIOS 2.70 07/01/2021 Workqueue: btrfs-endio btrfs_end_bio_work [btrfs] RIP: 0010:repair_io_failure+0x24a/0x260 [btrfs] Call Trace: <TASK> clean_io_failure+0x14d/0x180 [btrfs] end_bio_extent_readpage+0x412/0x6e0 [btrfs] ? __switch_to+0x106/0x420 process_one_work+0x1c7/0x380 worker_thread+0x4d/0x380 ? rescuer_thread+0x3a0/0x3a0 kthread+0xe9/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x22/0x30 [CAUSE] Before the BUG_ON(), we got some read errors from the replace target first, note the mirror number (3, which is beyond RAID1 duplication, thus it's read from the replace target device). Then at the BUG_ON() location, we are trying to writeback the repaired sectors back the failed device. The check looks like this: ret = btrfs_map_block(fs_info, BTRFS_MAP_WRITE, logical, &map_length, &bioc, mirror_num); if (ret) goto out_counter_dec; BUG_ON(mirror_num != bioc->mirror_num); But inside btrfs_map_block(), we can modify bioc->mirror_num especially for dev-replace: if (dev_replace_is_ongoing && mirror_num == map->num_stripes + 1 && !need_full_stripe(op) && dev_replace->tgtdev != NULL) { ret = get_extra_mirror_from_replace(fs_info, logical, *length, dev_replace->srcdev->devid, &mirror_num, &physical_to_patch_in_first_stripe); patch_the_first_stripe_for_dev_replace = 1; } Thus if we're repairing the replace target device, we're going to trigger that BUG_ON(). But in reality, the read failure from the replace target device may be that, our replace hasn't reached the range we're reading, thus we're reading garbage, but with replace running, the range would be properly filled later. Thus in that case, we don't need to do anything but let the replace routine to handle it. [FIX] Instead of a BUG_ON(), just skip the repair if we're repairing the device replace target device.
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Meta Information
Published
2025-12-30
Last Modified
2025-12-30
Generated
2026-05-07
AI Q&A
2025-12-30
EPSS Evaluated
2026-05-05
NVD
CVE-2023-54180
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel 6.0
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is a bug in the Linux kernel's btrfs filesystem related to handling disk replacement (dev-replace). When replacing an unreliable disk, a BUG_ON() check in the btrfs_repair_io_failure() function could be triggered incorrectly. This happens because the code tries to repair read errors from the replace target device, but due to how the replacement process works, some read failures are expected and should be handled by the replace routine instead of triggering a bug. The fix was to skip the repair step when dealing with the replace target device instead of causing a kernel bug.


How can this vulnerability impact me? :

This vulnerability can cause the Linux kernel to crash (kernel BUG) during disk replacement operations in btrfs, leading to system instability or downtime. It may interrupt the disk replacement process and potentially cause data access issues while the bug is triggered.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring kernel logs for specific BTRFS warnings and kernel BUG messages related to btrfs_repair_io_failure(). You should look for log entries similar to: 'BTRFS warning (device sda1): csum failed ...' and 'kernel BUG at fs/btrfs/extent_io.c:2380!'. Commands to check these logs include: 'dmesg | grep -i btrfs', 'journalctl -k | grep btrfs', or 'grep btrfs /var/log/kern.log'. These commands help identify if the BUG_ON() in btrfs_repair_io_failure() has been triggered due to disk replace operations.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves updating the Linux kernel to a version where this bug is fixed, which replaces the BUG_ON() with logic to skip repair when the device replace target is being repaired. Until then, monitor for the described kernel warnings and avoid interrupting ongoing device replace operations on BTRFS filesystems to prevent triggering the BUG_ON().


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