This patch adds the function page_check_range() to verify that pages are
in the cache and that they are appropriately readable/writable. It also
hooks up access_ok() to page_check_range() so that code patterns are
similar to kernel code.
When copying data from user space access_ok() is used to check that
pages are readable. When copying data to user space access_ok() is used
to check that pages are writable.
Index: qemu/exec.c
===================================================================
--- qemu.orig/exec.c 2007-10-31 10:49:10.000000000 -0600
+++ qemu/exec.c 2007-10-31 10:55:50.000000000 -0600
@@ -1875,6 +1875,33 @@
spin_unlock(&tb_lock);
}
+int page_check_range(target_ulong start, target_ulong len, int flags)
+{
+ PageDesc *p;
+ target_ulong end;
+ target_ulong addr;
+
+ end = TARGET_PAGE_ALIGN(start+len); /* must do before we loose bits in the next step */
+ start = start & TARGET_PAGE_MASK;
+
+ if( end < start )
+ /* we've wrapped around */
+ return -1;
+ for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {
+ p = page_find(addr >> TARGET_PAGE_BITS);
+ if( !p )
+ return -1;
+ if( !(p->flags & PAGE_VALID) )
+ return -1;
+
+ if (!(p->flags & PAGE_READ) && (flags & PAGE_READ) )
+ return -1;
+ if (!(p->flags & PAGE_WRITE) && (flags & PAGE_WRITE) )
+ return -1;
+ }
+ return 0;
+}
+
/* called from signal handler: invalidate the code and unprotect the
page. Return TRUE if the fault was succesfully handled. */
int page_unprotect(target_ulong address, unsigned long pc, void *puc)
Index: qemu/cpu-all.h
===================================================================
--- qemu.orig/cpu-all.h 2007-10-31 10:49:10.000000000 -0600
+++ qemu/cpu-all.h 2007-10-31 10:55:50.000000000 -0600
@@ -691,6 +691,7 @@
int page_get_flags(target_ulong address);
void page_set_flags(target_ulong start, target_ulong end, int flags);
void page_unprotect_range(target_ulong data, target_ulong data_size);
+int page_check_range(target_ulong start, target_ulong len, int flags);
CPUState *cpu_copy(CPUState *env);
Index: qemu/linux-user/qemu.h
===================================================================
--- qemu.orig/linux-user/qemu.h 2007-10-31 10:55:48.000000000 -0600
+++ qemu/linux-user/qemu.h 2007-10-31 10:55:50.000000000 -0600
@@ -185,7 +185,8 @@
#define VERIFY_READ 0
#define VERIFY_WRITE 1
-#define access_ok(type,addr,size) (1)
+#define access_ok(type,addr,size) \
+ (page_check_range((target_ulong)addr,size,(type==VERIFY_READ)?PAGE_READ:PAGE_WRITE)==0)
/* NOTE get_user and put_user use host addresses. */
#define __put_user(x,ptr)\
