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authorJesper Juhl <jj@chaosbits.net>2011-01-24 22:41:11 +0100
committerH. Peter Anvin <hpa@linux.intel.com>2011-01-24 13:46:15 -0800
commit2e5aa6824d9e0248d734573dad8858a2cc279cfe (patch)
tree535b372f88eee1ac3e56eda16c8618499f34fbaa /arch/x86/kernel/dumpstack_64.c
parentec30f343d61391ab23705e50a525da1d55395780 (diff)
x86-64: Don't use pointer to out-of-scope variable in dump_trace()
In arch/x86/kernel/dumpstack_64.c::dump_trace() we have this code: ... if (!stack) { unsigned long dummy; stack = &dummy; if (task && task != current) stack = (unsigned long *)task->thread.sp; } bp = stack_frame(task, regs); /* * Print function call entries in all stacks, starting at the * current stack address. If the stacks consist of nested * exceptions */ tinfo = task_thread_info(task); for (;;) { char *id; unsigned long *estack_end; estack_end = in_exception_stack(cpu, (unsigned long)stack, &used, &id); ... You'll notice that we assign to 'stack' the address of the variable 'dummy' which is only in-scope inside the 'if (!stack)'. So when we later access stack (at the end of the above, and assuming we did not take the 'if (task && task != current)' branch) we'll be using the address of a variable that is no longer in scope. I believe this patch is the proper fix, but I freely admit that I'm not 100% certain. Signed-off-by: Jesper Juhl <jj@chaosbits.net> LKML-Reference: <alpine.LNX.2.00.1101242232590.10252@swampdragon.chaosbits.net> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/dumpstack_64.c')
-rw-r--r--arch/x86/kernel/dumpstack_64.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 64101335de1..a6b6fcf7f0a 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -149,13 +149,13 @@ void dump_trace(struct task_struct *task,
unsigned used = 0;
struct thread_info *tinfo;
int graph = 0;
+ unsigned long dummy;
unsigned long bp;
if (!task)
task = current;
if (!stack) {
- unsigned long dummy;
stack = &dummy;
if (task && task != current)
stack = (unsigned long *)task->thread.sp;