lkml.org 
[lkml]   [2016]   [Jun]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v4 13/16] x86/dumpstack: Try harder to get a call trace on stack overflow
Date
If we overflow the stack, print_context_stack will abort.  Detect
this case and rewind back into the valid part of the stack so that
we can trace it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/kernel/dumpstack.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 4592bc4ed3e1..4538f7ca9072 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -87,7 +87,7 @@ static inline int valid_stack_ptr(struct task_struct *task,
else
return 0;
}
- return p > t && p < t + THREAD_SIZE - size;
+ return p >= t && p < t + THREAD_SIZE - size;
}

unsigned long
@@ -98,6 +98,13 @@ print_context_stack(struct task_struct *task,
{
struct stack_frame *frame = (struct stack_frame *)bp;

+ /*
+ * If we overflowed the stack into a guard page, jump back to the
+ * bottom of the usable stack.
+ */
+ if ((unsigned long)task->stack - (unsigned long)stack < PAGE_SIZE)
+ stack = (unsigned long *)task->stack;
+
while (valid_stack_ptr(task, stack, sizeof(*stack), end)) {
unsigned long addr;

--
2.5.5
\
 
 \ /
  Last update: 2016-06-24 07:01    [W:0.123 / U:0.408 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site