CVE intelligence and bounded remediation

CVE-2023-52737 — Linux Linux Kernel security vulnerability

Medium CVSS 5.5

In the Linux kernel, the following vulnerability has been resolved: btrfs: lock the inode in shared mode before starting fiemap Currently fiemap does not take the inode's lock (VFS lock), it only locks a file range in the inode's io tree. This however can lead to a deadlock if we have a concurrent fsync on the file and fiemap code triggers a fault when accessing the user space buffer with fiemap_fill_next_extent(). The deadlock happens on the inode's i_mmap_lock semaphore, which is taken both by fsync and btrfs_page_mkwrite(). This deadlock was recently reported by syzbot and triggers a trace like the following: task:syz-executor361 state:D stack:20264 pid:5668 ppid:5119 flags:0x00004004 Call Trace: <TASK> context_switch kernel/sched/core.c:5293 [inline] __schedule+0x995/0xe20 kernel/sched/core.c:6606 schedule+0xcb/0x190 kernel/sched/core.c:6682 wait_on_state fs/btrfs/extent-io-tree.c:707 [inline] wait_extent_bit+0x577/0x6f0 fs/btrfs/extent-io-tree.c:751 lock_extent+0x1c2/0x280 fs/btrfs/extent-io-tree.c:1742 find_lock_delalloc_range+0x4e6/0x9c0 fs/btrfs/extent_io.c:488 writepage_delalloc+0x1ef/0x540 fs/btrfs/extent_io.c:1863 __extent_writepage+0x736/0x14e0 fs/btrfs/extent_io.c:217…

Severity
Medium
CVSS
5.5 (3.1)
Published
2024-05-21
CISA KEV
Not currently listed
Ecosystem
linux/kernel
Weaknesses
CWE-667

Affected products

  • linux / linux_kernel
  • linux / linux_kernel / 6.2

Showing 2 representative product identities from 8 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Race condition, TOCTOU, and lifecycle synchronization

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Check exposure

  • Map concurrent actors, shared state, lock boundaries, signals, callbacks, retries, and check-then-use sequences in the affected path.
  • Determine whether untrusted users can influence timing, object names, filesystem state, or repeated state transitions.
  • Identify clustered and multi-process behavior that repository-local tests may not represent.

Remediate safely

  • Make the sensitive state transition atomic or protect it with a consistently ordered synchronization primitive.
  • Perform authorization and invariant checks on the same authoritative object and transaction used for the operation.
  • Use unique private resources, safe ownership transfer, and idempotent operations; add deterministic concurrency regression tests.

Authoritative sources

Complete CVE record and remediation plan

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