CVE-2026-64426

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

iouring/nop: fix file reference leak with IOSQEFIXED_FILE

NOP file-acquisition support choses between a fixed (registered) file and a normal fget()'d file based on its own IORINGNOPFIXEDFILE flag in sqe->nopflags. However, a request's REQFFIXEDFILE is set independently from the generic IOSQEFIXED_FILE sqe flag during request init, before the issue handler runs.

If a NOP is submitted with IOSQEFIXEDFILE set (so REQFFIXEDFILE is set) but without IORINGNOPFIXEDFILE, ionop() takes the normal path and grabs a real reference via iofilegetnormal(). On completion, ioputfile() only drops the reference when REQFFIXED_FILE is clear, so the fget()'d file is never released and leaks:

BUG: memory leak unreferenced object 0xffff88800f42c240 (size 176): kmemcacheallocnoprof+0x358/0x440 allocemptyfile+0x57/0x180 pathopenat+0x44/0x1e50 dofileopen+0x121/0x200 dosysopenat2+0xa7/0x150 __x64sysopenat+0x82/0xf0

Decide between fixed and normal file acquisition from REQFFIXEDFILE, the same way ioassignfile() does for every other opcode, and fold IORINGNOPFIXEDFILE into REQFFIXED_FILE at prep time.