Commit 5de253cc authored Apr 09, 2008 by Roland McGrath Committed by Ingo Molnar Apr 17, 2008

x86 vDSO: don't map 32-bit vdso when disabled



We map a VMA for the 32-bit vDSO even when it's disabled, which is stupid.
For the 32-bit kernel it's the vdso_enabled boot parameter/sysctl
and for the 64-bit kernel it's the vdso32 boot parameter/syscall32 sysctl.

When it's disabled, we don't pass AT_SYSINFO_EHDR so processes don't use
the vDSO for anything, but we still map it.  For the non-compat vDSO,
this means we're always putting an extra VMA somewhere, maybe lousing
up the control of the address space the user was hoping for.

Honor the setting by doing nothing in arch_setup_additional_pages.

[ also see: "x86 vDSO: don't use disabled vDSO for signal trampoline" ]

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 1a3e4ca4

arch/x86/vdso/vdso32-setup.c

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -325,6 +325,9 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
	int ret = 0;		int ret = 0;
	bool compat;		bool compat;

			if (vdso_enabled == VDSO_DISABLED)
			return 0;

	down_write(&mm->mmap_sem);		down_write(&mm->mmap_sem);

	/* Test compat mode once here, in case someone		/* Test compat mode once here, in case someone