Re: 2.6.26-rc: SPARC: Sun Ultra 10 can not boot

[David Miller <davem@davemloft.net>]

From: "Alexander Beregalov" <a.beregalov@gmail.com>
Date: Mon, 7 Jul 2008 19:59:04 +0400

> I have turned off LOCKDEP and it boots properly.
> 2.6.26-rc9-00005-g1b40a89
> 
> Mikael's config also does not contain LOCKDEP.

I have finally reproduced the problem locally and figured out the
bug.

Please try this patch:

sparc64: Fix end-of-stack checking in save_stack_trace().

Bug reported by Alexander Beregalov.

Before we dereference the stack frame or try to peek at the
pt_regs magic value, make sure the entire object is within
the kernel stack bounds.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc64/kernel/stacktrace.c b/arch/sparc64/kernel/stacktrace.c
index c73ce3f..c5576e8 100644
--- a/arch/sparc64/kernel/stacktrace.c
+++ b/arch/sparc64/kernel/stacktrace.c
@@ -25,13 +25,15 @@ void save_stack_trace(struct stack_trace *trace)
 
 		/* Bogus frame pointer? */
 		if (fp < (thread_base + sizeof(struct thread_info)) ||
-		    fp >= (thread_base + THREAD_SIZE))
+		    fp > (thread_base + THREAD_SIZE - sizeof(struct sparc_stackf)))
 			break;
 
 		sf = (struct sparc_stackf *) fp;
 		regs = (struct pt_regs *) (sf + 1);
 
-		if ((regs->magic & ~0x1ff) == PT_REGS_MAGIC) {
+		if (((unsigned long)regs <=
+		     (thread_base + THREAD_SIZE - sizeof(*regs))) &&
+		    (regs->magic & ~0x1ff) == PT_REGS_MAGIC) {
 			if (!(regs->tstate & TSTATE_PRIV))
 				break;
 			pc = regs->tpc;