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authorShu Wang <shuwang@redhat.com>2017-09-12 10:14:54 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-12 11:51:24 +0200
commita3ec104976f799808c2c1d8b32005c67b0037adb (patch)
treecfc67a5b3b4646e805f1d7884beaf4d4595bbcc6 /kernel/trace
parent3ff8bc813b1301ee1395b4629b5136559e3fc6ba (diff)
ftrace: Fix kmemleak in unregister_ftrace_graph
commit 2b0b8499ae75df91455bbeb7491d45affc384fb0 upstream. The trampoline allocated by function tracer was overwriten by function_graph tracer, and caused a memory leak. The save_global_trampoline should have saved the previous trampoline in register_ftrace_graph() and restored it in unregister_ftrace_graph(). But as it is implemented, save_global_trampoline was only used in unregister_ftrace_graph as default value 0, and it overwrote the previous trampoline's value. Causing the previous allocated trampoline to be lost. kmmeleak backtrace: kmemleak_vmalloc+0x77/0xc0 __vmalloc_node_range+0x1b5/0x2c0 module_alloc+0x7c/0xd0 arch_ftrace_update_trampoline+0xb5/0x290 ftrace_startup+0x78/0x210 register_ftrace_function+0x8b/0xd0 function_trace_init+0x4f/0x80 tracing_set_tracer+0xe6/0x170 tracing_set_trace_write+0x90/0xd0 __vfs_write+0x37/0x170 vfs_write+0xb2/0x1b0 SyS_write+0x55/0xc0 do_syscall_64+0x67/0x180 return_from_SYSCALL_64+0x0/0x6a [ Looking further into this, I found that this was left over from when the function and function graph tracers shared the same ftrace_ops. But in commit 5f151b2401 ("ftrace: Fix function_profiler and function tracer together"), the two were separated, and the save_global_trampoline no longer was necessary (and it may have been broken back then too). -- Steven Rostedt ] Link: http://lkml.kernel.org/r/20170912021454.5976-1-shuwang@redhat.com Fixes: 5f151b2401 ("ftrace: Fix function_profiler and function tracer together") Signed-off-by: Shu Wang <shuwang@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/ftrace.c14
1 files changed, 0 insertions, 14 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 53ed8ae5de1c..5b8d7189e147 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4381,9 +4381,6 @@ static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;
static char ftrace_graph_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
static int ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer);
-static unsigned long save_global_trampoline;
-static unsigned long save_global_flags;
-
static int __init set_graph_function(char *str)
{
strlcpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE);
@@ -5981,17 +5978,6 @@ void unregister_ftrace_graph(void)
unregister_pm_notifier(&ftrace_suspend_notifier);
unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
-#ifdef CONFIG_DYNAMIC_FTRACE
- /*
- * Function graph does not allocate the trampoline, but
- * other global_ops do. We need to reset the ALLOC_TRAMP flag
- * if one was used.
- */
- global_ops.trampoline = save_global_trampoline;
- if (save_global_flags & FTRACE_OPS_FL_ALLOC_TRAMP)
- global_ops.flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
-#endif
-
out:
mutex_unlock(&ftrace_lock);
}