Bug 2507179 (CVE-2026-64263) - CVE-2026-64263 kernel: fuse-uring: fix moving cancelled entry to ent_in_userspace list
Summary: CVE-2026-64263 kernel: fuse-uring: fix moving cancelled entry to ent_in_users...
Keywords:
Status: NEW
Alias: CVE-2026-64263
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
unspecified
unspecified
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-25 10:09 UTC by OSIDB Bzimport
Modified: 2026-07-29 13:31 UTC (History)
2 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-07-25 10:09:12 UTC
In the Linux kernel, the following vulnerability has been resolved:

fuse-uring: fix moving cancelled entry to ent_in_userspace list

fuse_uring_cancel() moves entries that are available (these have no reqs
attached) to the ent_in_userspace list. ent_list_request_expired()
checks the first entry on ent_in_userspace and dereferences
ent->fuse_req unconditionally, which will crash on a cancelled entry
that was moved to this list.

Fix this by freeing the entry and dropping queue_refs directly in
fuse_uring_cancel(). This is safe because cancel is the cancel handler
itself - after io_uring_cmd_done(), no more cancels will be dispatched
for this command, and teardown serializes with cancel via queue->lock.

Since cancel now decrements queue_refs, fuse_uring_abort() must no
longer gate fuse_uring_abort_end_requests() on queue_refs > 0, as
cancelled entries may have already dropped queue_refs while requests are
still queued. Remove the gate so abort always flushes requests and stops
queues.


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