fix perms/range of vsyscall vma in /proc/*/maps From: Ernie Petrides The final line of /proc//maps on x86_64 for native 64-bit tasks shows an incorrect ending address and incorrect permissions. There is only a single page mapped in this vsyscall region, and it is accessible for both read and execute. The patch below fixes this. (Since 32-bit-compat tasks have a real vma with correct perms/range, no change is necessary for that scenario.) Before the patch, a "cat /proc/self/maps | tail -1" shows this: ffffffffff600000-ffffffffffe00000 ---p 00000000 [...] After the patch, this is the output: ffffffffff600000-ffffffffff601000 r-xp 00000000 [...] Signed-off-by: Ernie Petrides Signed-off-by: Andi Kleen --- arch/x86_64/kernel/vsyscall.c | 1 + arch/x86_64/mm/init.c | 7 ++++--- include/asm-x86_64/vsyscall.h | 1 + 3 files changed, 6 insertions(+), 3 deletions(-) Index: linux/arch/x86_64/kernel/vsyscall.c =================================================================== --- linux.orig/arch/x86_64/kernel/vsyscall.c +++ linux/arch/x86_64/kernel/vsyscall.c @@ -288,6 +288,7 @@ static void __init map_vsyscall(void) extern char __vsyscall_0; unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0); + /* Note that VSYSCALL_MAPPED_PAGES must agree with the code below. */ __set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL); } Index: linux/arch/x86_64/mm/init.c =================================================================== --- linux.orig/arch/x86_64/mm/init.c +++ linux/arch/x86_64/mm/init.c @@ -737,14 +737,15 @@ static __init int x8664_sysctl_init(void __initcall(x8664_sysctl_init); #endif -/* A pseudo VMAs to allow ptrace access for the vsyscall page. This only +/* A pseudo VMA to allow ptrace access for the vsyscall page. This only covers the 64bit vsyscall page now. 32bit has a real VMA now and does not need special handling anymore. */ static struct vm_area_struct gate_vma = { .vm_start = VSYSCALL_START, - .vm_end = VSYSCALL_END, - .vm_page_prot = PAGE_READONLY + .vm_end = VSYSCALL_START + (VSYSCALL_MAPPED_PAGES << PAGE_SHIFT), + .vm_page_prot = PAGE_READONLY_EXEC, + .vm_flags = VM_READ | VM_EXEC }; struct vm_area_struct *get_gate_vma(struct task_struct *tsk) Index: linux/include/asm-x86_64/vsyscall.h =================================================================== --- linux.orig/include/asm-x86_64/vsyscall.h +++ linux/include/asm-x86_64/vsyscall.h @@ -10,6 +10,7 @@ enum vsyscall_num { #define VSYSCALL_START (-10UL << 20) #define VSYSCALL_SIZE 1024 #define VSYSCALL_END (-2UL << 20) +#define VSYSCALL_MAPPED_PAGES 1 #define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr)) #ifdef __KERNEL__