CVE-2026-64067

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

netfs: Fix missing barriers when accessing stream->subrequests locklessly

The list of subrequests attached to stream->subrequests is accessed without

locks by netfscollectreadresults() and netfscollectwriteresults(),

and then they access subreq->flags without taking a barrier after getting

the subreq pointer from the list.  Relatedly, the functions that build the

list don't use any sort of write barrier when constructing the list to make

sure that the NETFSSREQIN_PROGRESS flag is perceived to be set first if

no lock is taken.

Fix this by:

 (1) Add a new listaddtail_release() function that uses a release barrier

     to set the pointer to the new member of the list.

 (2) Add a new listfirstentryornull_acquire() function that uses an

     acquire barrier to read the pointer to the first member in a list (or

     return NULL).

 (3) Use listaddtail_release() when adding a subreq to ->subrequests.

 (4) Use listfirstentryornull_acquire() when initially accessing the

     front of the list (when an item is removed, the pointer to the new

     front iterm is obtained under the same lock).