mprotect(EXEC) was failing for stack mappings as default vm flags was
missing MAYEXEC.
This was triggered by glibc test suite nptl/tst-execstack testcase
What is surprising is that despite running LTP for years on, we didn't
catch this issue as it lacks a directed test case.
gcc dejagnu tests with nested functions also requiring exec stack work
fine though because they rely on the GNU_STACK segment spit out by
compiler and handled in kernel elf loader.
This glibc case is different as the stack is non exec to begin with and
a dlopen of shared lib with GNU_STACK segment triggers the exec stack
proceedings using a mprotect(PROT_EXEC) which was broken.
CC: stable@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
93312b6da4