Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix failure to...
In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix failure to rebuild free space tree using multiple transactions
If we are rebuilding a free space tree, while modifying the free space
tree we may need to allocate a new metadata block group.
If we end up using multiple transactions for the rebuild, when we call
btrfs_end_transaction() we enter btrfs_create_pending_block_groups()
which calls add_block_group_free_space() to add items to the free space
tree for the block group.
Then later during the free space tree rebuild, at
btrfs_rebuild_free_space_tree(), we may find such new block groups
and call populate_free_space_tree() for them, which fails with -EEXIST
because there are already items in the free space tree. Then we abort the
transaction with -EEXIST at btrfs_rebuild_free_space_tree().
Notice that we say "may find" the new block groups because a new block
group may be inserted in the block groups rbtree, which is being iterated
by the rebuild process, before or after the current node where the rebuild
process is currently at.
Syzbot recently reported such case which produces a trace like the
following:
------------[ cut here ]------------
BTRFS: Transaction aborted (error -17)
WARNING: CPU: 1 PID: 7626 at fs/btrfs/free-space-tree.c:1341 btrfs_rebuild_free_space_tree+0x470/0x54c fs/btrfs/free-space-tree.c:1341
Modules linked in:
CPU: 1 UID: 0 PID: 7626 Comm: syz.2.25 Not tainted 6.15.0-rc7-syzkaller-00085-gd7fa1af5b33e-dirty #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : btrfs_rebuild_free_space_tree+0x470/0x54c fs/btrfs/free-space-tree.c:1341
lr : btrfs_rebuild_free_space_tree+0x470/0x54c fs/btrfs/free-space-tree.c:1341
sp : ffff80009c4f7740
x29: ffff80009c4f77b0 x28: ffff0000d4c3f400 x27: 0000000000000000
x26: dfff800000000000 x25: ffff70001389eee8 x24: 0000000000000003
x23: 1fffe000182b6e7b x22: 0000000000000000 x21: ffff0000c15b73d8
x20: 00000000ffffffef x19: ffff0000c15b7378 x18: 1fffe0003386f276
x17: ffff80008f31e000 x16: ffff80008adbe98c x15: 0000000000000001
x14: 1fffe0001b281550 x13: 0000000000000000 x12: 0000000000000000
x11: ffff60001b281551 x10: 0000000000000003 x9 : 1c8922000a902c00
x8 : 1c8922000a902c00 x7 : ffff800080485878 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000001 x3 : ffff80008047843c
x2 : 0000000000000001 x1 : ffff80008b3ebc40 x0 : 0000000000000001
Call trace:
btrfs_rebuild_free_space_tree+0x470/0x54c fs/btrfs/free-space-tree.c:1341 (P)
btrfs_start_pre_rw_mount+0xa78/0xe10 fs/btrfs/disk-io.c:3074
btrfs_remount_rw fs/btrfs/super.c:1319 [inline]
btrfs_reconfigure+0x828/0x2418 fs/btrfs/super.c:1543
reconfigure_super+0x1d4/0x6f0 fs/super.c:1083
do_remount fs/namespace.c:3365 [inline]
path_mount+0xb34/0xde0 fs/namespace.c:4200
do_mount fs/namespace.c:4221 [inline]
__do_sys_mount fs/namespace.c:4432 [inline]
__se_sys_mount fs/namespace.c:4409 [inline]
__arm64_sys_mount+0x3e8/0x468 fs/namespace.c:4409
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767
el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
irq event stamp: 330
hardirqs last enabled at (329): [] raw_spin_rq_unlock_irq kernel/sched/sched.h:1525 [inline]
hardirqs last enabled at (329): [] finish_lock_switch+0xb0/0x1c0 kernel/sched/core.c:5130
hardirqs last disabled at (330): [] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:511
softirqs last enabled at (10): [] local_bh_enable+0
---truncated---
Impact
CVE-2025-38370 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-38370? CVE-2025-38370 is a medium-severity security vulnerability. No fixed version is listed yet.
- How severe is CVE-2025-38370? CVE-2025-38370 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-38370? No fixed version is listed for CVE-2025-38370 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-38370 exploitable, and should I be worried? Whether CVE-2025-38370 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-38370 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.