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Diffstat (limited to 'arch/i386/oprofile/backtrace.c')
-rw-r--r--arch/i386/oprofile/backtrace.c38
1 files changed, 13 insertions, 25 deletions
diff --git a/arch/i386/oprofile/backtrace.c b/arch/i386/oprofile/backtrace.c
index 65dfd2e..21654be 100644
--- a/arch/i386/oprofile/backtrace.c
+++ b/arch/i386/oprofile/backtrace.c
@@ -12,6 +12,7 @@
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/ptrace.h>
+#include <asm/uaccess.h>
struct frame_head {
struct frame_head * ebp;
@@ -21,26 +22,22 @@ struct frame_head {
static struct frame_head *
dump_backtrace(struct frame_head * head)
{
- oprofile_add_trace(head->ret);
+ struct frame_head bufhead[2];
- /* frame pointers should strictly progress back up the stack
- * (towards higher addresses) */
- if (head >= head->ebp)
+ /* Also check accessibility of one struct frame_head beyond */
+ if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
+ return NULL;
+ if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
return NULL;
- return head->ebp;
-}
-
-/* check that the page(s) containing the frame head are present */
-static int pages_present(struct frame_head * head)
-{
- struct mm_struct * mm = current->mm;
+ oprofile_add_trace(bufhead[0].ret);
- /* FIXME: only necessary once per page */
- if (!check_user_page_readable(mm, (unsigned long)head))
- return 0;
+ /* frame pointers should strictly progress back up the stack
+ * (towards higher addresses) */
+ if (head >= bufhead[0].ebp)
+ return NULL;
- return check_user_page_readable(mm, (unsigned long)(head + 1));
+ return bufhead[0].ebp;
}
/*
@@ -97,15 +94,6 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
return;
}
-#ifdef CONFIG_SMP
- if (!spin_trylock(&current->mm->page_table_lock))
- return;
-#endif
-
- while (depth-- && head && pages_present(head))
+ while (depth-- && head)
head = dump_backtrace(head);
-
-#ifdef CONFIG_SMP
- spin_unlock(&current->mm->page_table_lock);
-#endif
}