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CVE-2025-21664

HIGH(7.8)

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Risk Signal Score20/100 — NIEDRIG
  • CVSS 7.8 — Hoch

Erwähnungen (letzte 60 Tage)

Artikel

EPSS-Score

0.2%

Exploit-Wahrscheinlichkeit (30 Tage)

CVSS Score

7.8

Technische Schwere

Beschreibung

In the Linux kernel, the following vulnerability has been resolved: dm thin: make get_first_thin use rcu-safe list first function The documentation in rculist.h explains the absence of list_empty_rcu() and cautions programmers against relying on a list_empty() -> list_first() sequence in RCU safe code. This is because each of these functions performs its own READ_ONCE() of the list head. This can lead to a situation where the list_empty() sees a valid list entry, but the subsequent list_first() sees a different view of list head state after a modification. In the case of dm-thin, this author had a production box crash from a GP fault in the process_deferred_bios path. This function saw a valid list head in get_first_thin() but when it subsequently dereferenced that and turned it into a thin_c, it got the inside of the struct pool, since the list was now empty and referring to itself. The kernel on which this occurred printed both a warning about a refcount_t being saturated, and a UBSAN error for an out-of-bounds cpuid access in the queued spinlock, prior to the fault itself. When the resulting kdump was examined, it was possible to see another thread patiently waiting in thin_dtr's synchronize_rcu. The thin_dtr call managed to pull the thin_c out of the active thins list (and have it be the last entry in the active_thins list) at just the wrong moment which lead to this crash. Fortunately, the fix here is straight forward. Switch get_first_thin() function to use list_first_or_null_rcu() which performs just a single READ_ONCE() and returns NULL if the list is already empty. This was run against the devicemapper test suite's thin-provisioning suites for delete and suspend and no regressions were observed.

Betroffene Produkte

  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:3.15:-:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:3.15:rc4:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:3.15:rc5:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:3.15:rc6:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:3.15:rc7:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:3.15:rc8:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:6.13:rc2:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:6.13:rc3:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:6.13:rc4:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:6.13:rc5:*:*:*:*:*:*
  • cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:*

Referenzen