4.9-stable review patch. If anyone has any objections, please let me know.
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From: Vineet Gupta vgupta@synopsys.com
commit 93312b6da4df31e4102ce5420e6217135a16c7ea upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/arc/include/asm/page.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/arc/include/asm/page.h +++ b/arch/arc/include/asm/page.h @@ -105,7 +105,7 @@ typedef pte_t * pgtable_t; #define virt_addr_valid(kaddr) pfn_valid(virt_to_pfn(kaddr))
/* Default Permissions for stack/heaps pages (Non Executable) */ -#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE) +#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
#define WANT_PAGE_VIRTUAL 1