The following patch fixes the 64 bit user code backtrace
which currently may hang the system.
Signed-off-by: Carl Love <carll@us.ibm.com>
Index: linux-2.6.25.1/arch/powerpc/oprofile/backtrace.c
===================================================================
--- linux-2.6.25.1.orig/arch/powerpc/oprofile/backtrace.c 2008-05-01 16:45:25.000000000 -0500
+++ linux-2.6.25.1/arch/powerpc/oprofile/backtrace.c 2008-05-07 11:29:02.000000000 -0500
@@ -53,19 +53,40 @@
#ifdef CONFIG_PPC64
static unsigned long user_getsp64(unsigned long sp, int is_first)
{
- unsigned long stack_frame[3];
+ unsigned long stk_frm_lr;
+ unsigned long stk_frm_sp;
+ unsigned long size;
+
+ /* Issue the __copy_from_user_inatomic() third argument currently
+ * only takes sizes 1, 2, 4 or 8 bytes. Don't read more then the
+ * first 48 bytes of the stack frame. That is all that is
+ * guaranteed to exist. Reading more may cause the system to hang.
+ *
+ * 64 bit stack frame layout:
+ * 0-7 bytes is the pointer to previous stack
+ * 8-15 bytes condition register save area
+ * 16-23 bytes link register save area
+ */
+ size = sizeof(unsigned long);
+ if (!access_ok(VERIFY_READ, (void __user *)sp, size))
+ return 0;
- if (!access_ok(VERIFY_READ, (void __user *)sp, sizeof(stack_frame)))
+ if (__copy_from_user_inatomic(&stk_frm_sp, (void __user *)sp,
+ size))
return 0;
- if (__copy_from_user_inatomic(stack_frame, (void __user *)sp,
- sizeof(stack_frame)))
+ /* get the LR from the user stack */
+ if (!access_ok(VERIFY_READ, (void __user *)(sp+16), size))
+ return 0;
+
+ if (__copy_from_user_inatomic(&stk_frm_lr, (void __user *)(sp+16),
+ size))
return 0;
if (!is_first)
- oprofile_add_trace(STACK_LR64(stack_frame));
+ oprofile_add_trace(stk_frm_lr);
- return STACK_SP(stack_frame);
+ return stk_frm_sp;
}
#endif
--
