CVE-2026-64253 PUBLISHED

kernel/fork: clear PF_BLOCK_TS in copy_process()

Assigner: Linux
Reserved: 19.07.2026 Published: 24.07.2026 Updated: 24.07.2026

In the Linux kernel, the following vulnerability has been resolved:

kernel/fork: clear PF_BLOCK_TS in copy_process()

PF_BLOCK_TS is only set in blk_time_get_ns() when current->plug is non-NULL, and blk_finish_plug() clears it via __blk_flush_plug() before NULLing the plug pointer. copy_process() breaks the invariant by inheriting PF_BLOCK_TS from the parent while resetting the child's plug to NULL.

Clear PF_BLOCK_TS alongside that assignment so callers can rely on "PF_BLOCK_TS set implies current->plug != NULL" and dereference current->plug unguarded.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from 06b23f92af87a84d70881b2ecaa72e00f7838264 to ee0801aceabdf583392477baf69a290b09448b8f (excl.)
  • affected from 06b23f92af87a84d70881b2ecaa72e00f7838264 to 99e6c712cc300883b8cbf03347d5359ec1a4d6dd (excl.)
  • affected from 06b23f92af87a84d70881b2ecaa72e00f7838264 to 77bba61a20f1b3d206f4f90e10a7bb3cd90b9619 (excl.)
  • affected from 06b23f92af87a84d70881b2ecaa72e00f7838264 to fd38b75c4b43295b10d69772a46d1c74dbd6fc81 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 6.9 is affected
  • unaffected from 0 to 6.9 (excl.)
  • unaffected from 6.12.95 to 6.12.* (incl.)
  • unaffected from 6.18.38 to 6.18.* (incl.)
  • unaffected from 7.1.3 to 7.1.* (incl.)
  • unaffected from 7.2-rc1 to * (incl.)

References