diff options
Diffstat (limited to 'arch/i386/oprofile/backtrace.c')
| -rw-r--r-- | arch/i386/oprofile/backtrace.c | 38 |
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(¤t->mm->page_table_lock)) - return; -#endif - - while (depth-- && head && pages_present(head)) + while (depth-- && head) head = dump_backtrace(head); - -#ifdef CONFIG_SMP - spin_unlock(¤t->mm->page_table_lock); -#endif } |