[PATCH] x86_64: TASK_SIZE fixes for compatibility mode processes
Appended patch will setup compatibility mode TASK_SIZE properly. This will
fix atleast three known bugs that can be encountered while running
compatibility mode apps.
a) A malicious 32bit app can have an elf section at 0xffffe000. During
exec of this app, we will have a memory leak as insert_vm_struct() is
not checking for return value in syscall32_setup_pages() and thus not
freeing the vma allocated for the vsyscall page. And instead of exec
failing (as it has addresses > TASK_SIZE), we were allowing it to
succeed previously.
b) With a 32bit app, hugetlb_get_unmapped_area/arch_get_unmapped_area
may return addresses beyond 32bits, ultimately causing corruption
because of wrap-around and resulting in SEGFAULT, instead of returning
ENOMEM.
c) 32bit app doing this below mmap will now fail.
mmap((void *)(0xFFFFE000UL), 0x10000UL, PROT_READ|PROT_WRITE,
MAP_FIXED|MAP_PRIVATE|MAP_ANON, 0, 0);
Signed-off-by: Zou Nan hai <nanhai.zou@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-x86_64/a.out.h b/include/asm-x86_64/a.out.h
index 5952914..7255cde 100644
--- a/include/asm-x86_64/a.out.h
+++ b/include/asm-x86_64/a.out.h
@@ -21,7 +21,7 @@
#ifdef __KERNEL__
#include <linux/thread_info.h>
-#define STACK_TOP (test_thread_flag(TIF_IA32) ? IA32_PAGE_OFFSET : TASK_SIZE)
+#define STACK_TOP TASK_SIZE
#endif
#endif /* __A_OUT_GNU_H__ */
diff --git a/include/asm-x86_64/processor.h b/include/asm-x86_64/processor.h
index d641b19..8b55f13 100644
--- a/include/asm-x86_64/processor.h
+++ b/include/asm-x86_64/processor.h
@@ -160,16 +160,17 @@
/*
* User space process size. 47bits minus one guard page.
*/
-#define TASK_SIZE (0x800000000000UL - 4096)
+#define TASK_SIZE64 (0x800000000000UL - 4096)
/* This decides where the kernel will search for a free chunk of vm
* space during mmap's.
*/
#define IA32_PAGE_OFFSET ((current->personality & ADDR_LIMIT_3GB) ? 0xc0000000 : 0xFFFFe000)
-#define TASK_UNMAPPED_32 PAGE_ALIGN(IA32_PAGE_OFFSET/3)
-#define TASK_UNMAPPED_64 PAGE_ALIGN(TASK_SIZE/3)
-#define TASK_UNMAPPED_BASE \
- (test_thread_flag(TIF_IA32) ? TASK_UNMAPPED_32 : TASK_UNMAPPED_64)
+
+#define TASK_SIZE (test_thread_flag(TIF_IA32) ? IA32_PAGE_OFFSET : TASK_SIZE64)
+#define TASK_SIZE_OF(child) ((test_tsk_thread_flag(child, TIF_IA32)) ? IA32_PAGE_OFFSET : TASK_SIZE64)
+
+#define TASK_UNMAPPED_BASE PAGE_ALIGN(TASK_SIZE/3)
/*
* Size of io_bitmap.
