CVE-2022-50090
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-06-18

Last updated on: 2025-11-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: replace BTRFS_MAX_EXTENT_SIZE with fs_info->max_extent_size On zoned filesystem, data write out is limited by max_zone_append_size, and a large ordered extent is split according the size of a bio. OTOH, the number of extents to be written is calculated using BTRFS_MAX_EXTENT_SIZE, and that estimated number is used to reserve the metadata bytes to update and/or create the metadata items. The metadata reservation is done at e.g, btrfs_buffered_write() and then released according to the estimation changes. Thus, if the number of extent increases massively, the reserved metadata can run out. The increase of the number of extents easily occurs on zoned filesystem if BTRFS_MAX_EXTENT_SIZE > max_zone_append_size. And, it causes the following warning on a small RAM environment with disabling metadata over-commit (in the following patch). [75721.498492] ------------[ cut here ]------------ [75721.505624] BTRFS: block rsv 1 returned -28 [75721.512230] WARNING: CPU: 24 PID: 2327559 at fs/btrfs/block-rsv.c:537 btrfs_use_block_rsv+0x560/0x760 [btrfs] [75721.581854] CPU: 24 PID: 2327559 Comm: kworker/u64:10 Kdump: loaded Tainted: G W 5.18.0-rc2-BTRFS-ZNS+ #109 [75721.597200] Hardware name: Supermicro Super Server/H12SSL-NT, BIOS 2.0 02/22/2021 [75721.607310] Workqueue: btrfs-endio-write btrfs_work_helper [btrfs] [75721.616209] RIP: 0010:btrfs_use_block_rsv+0x560/0x760 [btrfs] [75721.646649] RSP: 0018:ffffc9000fbdf3e0 EFLAGS: 00010286 [75721.654126] RAX: 0000000000000000 RBX: 0000000000004000 RCX: 0000000000000000 [75721.663524] RDX: 0000000000000004 RSI: 0000000000000008 RDI: fffff52001f7be6e [75721.672921] RBP: ffffc9000fbdf420 R08: 0000000000000001 R09: ffff889f8d1fc6c7 [75721.682493] R10: ffffed13f1a3f8d8 R11: 0000000000000001 R12: ffff88980a3c0e28 [75721.692284] R13: ffff889b66590000 R14: ffff88980a3c0e40 R15: ffff88980a3c0e8a [75721.701878] FS: 0000000000000000(0000) GS:ffff889f8d000000(0000) knlGS:0000000000000000 [75721.712601] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [75721.720726] CR2: 000055d12e05c018 CR3: 0000800193594000 CR4: 0000000000350ee0 [75721.730499] Call Trace: [75721.735166] <TASK> [75721.739886] btrfs_alloc_tree_block+0x1e1/0x1100 [btrfs] [75721.747545] ? btrfs_alloc_logged_file_extent+0x550/0x550 [btrfs] [75721.756145] ? btrfs_get_32+0xea/0x2d0 [btrfs] [75721.762852] ? btrfs_get_32+0xea/0x2d0 [btrfs] [75721.769520] ? push_leaf_left+0x420/0x620 [btrfs] [75721.776431] ? memcpy+0x4e/0x60 [75721.781931] split_leaf+0x433/0x12d0 [btrfs] [75721.788392] ? btrfs_get_token_32+0x580/0x580 [btrfs] [75721.795636] ? push_for_double_split.isra.0+0x420/0x420 [btrfs] [75721.803759] ? leaf_space_used+0x15d/0x1a0 [btrfs] [75721.811156] btrfs_search_slot+0x1bc3/0x2790 [btrfs] [75721.818300] ? lock_downgrade+0x7c0/0x7c0 [75721.824411] ? free_extent_buffer.part.0+0x107/0x200 [btrfs] [75721.832456] ? split_leaf+0x12d0/0x12d0 [btrfs] [75721.839149] ? free_extent_buffer.part.0+0x14f/0x200 [btrfs] [75721.846945] ? free_extent_buffer+0x13/0x20 [btrfs] [75721.853960] ? btrfs_release_path+0x4b/0x190 [btrfs] [75721.861429] btrfs_csum_file_blocks+0x85c/0x1500 [btrfs] [75721.869313] ? rcu_read_lock_sched_held+0x16/0x80 [75721.876085] ? lock_release+0x552/0xf80 [75721.881957] ? btrfs_del_csums+0x8c0/0x8c0 [btrfs] [75721.888886] ? __kasan_check_write+0x14/0x20 [75721.895152] ? do_raw_read_unlock+0x44/0x80 [75721.901323] ? _raw_write_lock_irq+0x60/0x80 [75721.907983] ? btrfs_global_root+0xb9/0xe0 [btrfs] [75721.915166] ? btrfs_csum_root+0x12b/0x180 [btrfs] [75721.921918] ? btrfs_get_global_root+0x820/0x820 [btrfs] [75721.929166] ? _raw_write_unlock+0x23/0x40 [75721.935116] ? unpin_extent_cache+0x1e3/0x390 [btrfs] [75721.942041] btrfs_finish_ordered_io.isra.0+0xa0c/0x1dc0 [btrfs] [75721.949906] ? try_to_wake_up+0x30/0x14a0 [75721.955700] ? btrfs_unlink_subvol+0xda0/0xda0 [btrfs] [75721.962661] ? rcu ---truncated---
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Meta Information
Published
2025-06-18
Last Modified
2025-11-18
Generated
2026-05-07
AI Q&A
2025-06-18
EPSS Evaluated
2026-05-05
NVD
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
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CWE ID Description
CWE-NVD-CWE-noinfo
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability in the Linux kernel's Btrfs filesystem arises because the system uses a fixed maximum extent size (BTRFS_MAX_EXTENT_SIZE) to estimate metadata reservation, while on zoned filesystems, the actual data write size is limited by max_zone_append_size and large extents are split accordingly. If BTRFS_MAX_EXTENT_SIZE is larger than max_zone_append_size, the number of extents increases significantly, causing the reserved metadata space to run out. This can lead to warnings and potential failures in metadata reservation during writes, especially in environments with limited RAM and disabled metadata over-commit.


How can this vulnerability impact me? :

The vulnerability can cause the Linux kernel to run out of reserved metadata space during writes on zoned filesystems, leading to warnings and potential write failures. This can affect system stability and data integrity during file operations, particularly on systems with small RAM and specific configurations that disable metadata over-commit.


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

This vulnerability can be detected by monitoring the system logs for specific warning messages related to BTRFS metadata reservation failures. Look for kernel log entries containing warnings such as 'BTRFS: block rsv 1 returned -28' and 'WARNING: CPU: ... btrfs_use_block_rsv'. You can use the command 'dmesg | grep -i btrfs' or 'journalctl -k | grep -i btrfs' to search for these messages in the kernel logs.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include updating the Linux kernel to a version where this vulnerability is resolved, which replaces BTRFS_MAX_EXTENT_SIZE with fs_info->max_extent_size to properly handle metadata reservation on zoned filesystems. Additionally, avoid disabling metadata over-commit on systems with small RAM to prevent running out of reserved metadata bytes.


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