diff options
| author | Deepesh Gujarathi <dgujarathi@nvidia.com> | 2011-04-20 17:17:39 +0530 |
|---|---|---|
| committer | Varun Colbert <vcolbert@nvidia.com> | 2011-04-20 22:24:07 -0700 |
| commit | 7658942c9866ae6299a7b50735007ae763b303e6 (patch) | |
| tree | 0abe8b9b906c6665b1a254eaacf518895a117fb9 /arch/arm/kernel | |
| parent | edb1ab30472bff7fb9871a00db8720c2b51d9c21 (diff) | |
ARM: fix /proc/$PID/stack on SMP
Rabin Vincent reports:
| On SMP, this BUG() in save_stack_trace_tsk() can be easily triggered
| from user space by reading /proc/$PID/stack, where $PID is any pid but
| the current process:
|
| if (tsk != current) {
| #ifdef CONFIG_SMP
| /*
| * What guarantees do we have here that 'tsk'
| * is not running on another CPU?
| */
| BUG();
| #else
Fix this by replacing the BUG() with an entry to terminate the stack
trace, returning an empty trace - I'd rather not expose the dwarf
unwinder to a volatile stack of a running thread.
Change-Id: Ide38bb5eeff09c1d1189bc1a30667a2cc6b96ba2
Reported-by: Rabin Vincent <rabin@rab.in>
Tested-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-on: http://git-master/r/28325
Reviewed-by: Varun Colbert <vcolbert@nvidia.com>
Tested-by: Varun Colbert <vcolbert@nvidia.com>
Diffstat (limited to 'arch/arm/kernel')
| -rw-r--r-- | arch/arm/kernel/stacktrace.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c index 20b7411e47fd..f9e160816961 100644 --- a/arch/arm/kernel/stacktrace.c +++ b/arch/arm/kernel/stacktrace.c @@ -94,10 +94,13 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) if (tsk != current) { #ifdef CONFIG_SMP /* - * What guarantees do we have here that 'tsk' - * is not running on another CPU? + * What guarantees do we have here that 'tsk' is not + * running on another CPU? For now, ignore it as we + * can't guarantee we won't explode. */ - BUG(); + if (trace->nr_entries < trace->max_entries) + trace->entries[trace->nr_entries++] = ULONG_MAX; + return; #else data.no_sched_functions = 1; frame.fp = thread_saved_fp(tsk); |