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CVE-2026-80920

io_uring: defer eventfd signaling when queued from a wakeup handler PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: io_uring: defer eventfd signaling when queued from a wakeup handler io_req_local_work_add() signals the CQ ring eventfd inline when it is the one to push the first entry onto ->work_list. For DEFER_TASKRUN rings that add is frequently done from a waitqueue wakeup handler, where an arbitrary waitqueue lock is held. eventfd_signal_mask() only refuses to recurse when current->in_eventfd is set, but that bit is set by eventfd_signal_mask() itself. If the wake chain starts somewhere else, signal goes out inline and can feed back into epoll. Add IOU_F_TWQ_IN_WAKE, set it on the task_work add done from the three waitqueue callbacks, and use it to force io_eventfd_signal() down the existing call_rcu_hurry() deferral instead of signaling inline.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 21a091b970cdbcf3e8ff829234b51be6f9192766 before d0c240f25e654442a72af5ca021a02165ccce638; affected 21a091b970cdbcf3e8ff829234b51be6f9192766 before 9d984451baf768ecd9e1fdad4637b729fcb2c9d5; affected 21a091b970cdbcf3e8ff829234b51be6f9192766 before e22f4494cc9487d326e5e3067f33dea7c1e442b2; affected 21a091b970cdbcf3e8ff829234b51be6f9192766 before b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f; affected 21a091b970cdbcf3e8ff829234b51be6f9192766 before 40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a; affected 21a091b970cdbcf3e8ff829234b51be6f9192766 before cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e
Linux / Linuxaffected 6.1; unaffected 0 before 6.1; unaffected 6.6.160 through 6.6.*; unaffected 6.12.114 through 6.12.*; unaffected 6.18.49 through 6.18.*; unaffected 7.1.11 through 7.1.*; unaffected 7.2.1 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References