In the Linux kernel, the following vulnerability has been resolved:
s390/percpu: Fix MVIY_PERCPU() with older binutils
Commit a737737cdb9c ("s390/percpu: Infrastructure for more efficient
this_cpu operations") introduced MVIY_PERCPU(), which stringifies
arguments that are already C string literals. This generates an
assembler macro invocation with whitespace-separated quoted arguments:
GEN_MVIY "459712" "%r3"
GNU as versions prior to binutils 2.39 drop the separating whitespace
between quoted macro arguments during input scrubbing. They
consequently parse the invocation as a single argument and emit
repeated warnings:
Warning: missing closing `"'
The .ifc in GEN_MVIY never matches and GNU as exits successfully
without emitting the mviy instruction.
As a result, the interrupted
per-CPU sequence is not marked in lowcore and the exception return
path cannot repair the per-CPU address register after migration. All MVIY_PERCPU() callers pass C string literals. Use them directly
and separate the assembler macro arguments with an explicit comma.
The
resulting invocation is:
GEN_MVIY 459712, %r3
This form is unambiguous for GNU as and LLVM's integrated assembler. This behavior was fixed in GNU as from binutils 2.39, but Linux
supports binutils 2.30.
Attack Parameters
Impact Assessment
CVSS Vector v3.1