CVE-2025-37856High· 7.8▾ TwilightIn the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 42.9 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Oct 21.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
Last analysed / modified upstream
0.3%
0.3% → 0.3%
In the Linux kernel, the following vulnerability has been resolved:
btrfs: harden block_group::bg_list against list_del() races
As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly.
However, if there is any chance at all of racing with mark_bg_unused(), or a different future user of bg_list, better to be safe than sorry.
Otherwise we risk the following interleaving (bg_list refcount in parens)
T1 (some random op) T2 (btrfs_mark_bg_unused) !list_empty(&bg->bg_list); (1) list_del_init(&bg->bg_list); (1) list_move_tail (1) btrfs_put_block_group (0) btrfs_delete_unused_bgs bg = list_first_entry list_del_init(&bg->bg_list); btrfs_put_block_group(bg); (-1)
Ultimately, this results in a broken ref count that hits zero one deref early and the real final deref underflows the refcount, resulting in a WARNING.
Linux >= a9f189716cf15913c453299d72f69c51a9b0f86b < 9039afe6240ae01d6caf2fa731590ac74fb8a69bLinux >= a9f189716cf15913c453299d72f69c51a9b0f86b < bf089c4d1141b27332c092b1dcca5022c415a3b6Linux >= a9f189716cf15913c453299d72f69c51a9b0f86b < 909e60fb469d4101c6b08cf6e622efb062bb24a1Linux >= a9f189716cf15913c453299d72f69c51a9b0f86b < 185fd73e5ac06027c4be9a129e59193f6a3ef202Linux >= a9f189716cf15913c453299d72f69c51a9b0f86b < 7511e29cf1355b2c47d0effb39e463119913e2f6Linux edf3b5aadb2515c808200b904baa5b70a727f0acLinux 01eca70ef8cf499d0cb6d1bbd691558e7792cf17Linux 5d19abcffd8404078dfa7d7118cec357b5e7bc58Linux >= 5.15.128 < 5.16Linux >= 6.1.47 < 6.2Linux >= 6.4.12 < 6.5Linux 6.5Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
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