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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2018-01-11 19:47:46 -0500
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-01-17 10:22:08 -0300
commit37db96bb49629681cb839d7304a70524fe10f969 (patch)
tree3eae8bf095d1c639f9a8d91d35c15293f6cda6de /tools/lib
parent38d70b7ca1769f26c0b79f3c08ff2cc949712b59 (diff)
tools lib traceevent: Handle new pointer processing of bprint strings
The Linux kernel printf() has some extended use cases that dereference the pointer. This is dangerouse for tracing because the pointer that is dereferenced can change or even be unmapped. It also causes issues when the trace data is extracted, because user space does not have access to the contents of the pointer even if it still exists. To handle this, the kernel was updated to process these dereferenced pointers at the time they are recorded, and not post processed. Now they exist in the tracing buffer, and no dereference is needed at the time of reading the trace. The event parsing library needs to handle this new case. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20180112004822.403349289@goodmis.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/lib')
-rw-r--r--tools/lib/traceevent/event-parse.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 8757dd64e42c..344a034a8fbc 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -4300,6 +4300,26 @@ static struct print_arg *make_bprint_args(char *fmt, void *data, int size, struc
goto process_again;
case 'p':
ls = 1;
+ if (isalnum(ptr[1])) {
+ ptr++;
+ /* Check for special pointers */
+ switch (*ptr) {
+ case 's':
+ case 'S':
+ case 'f':
+ case 'F':
+ break;
+ default:
+ /*
+ * Older kernels do not process
+ * dereferenced pointers.
+ * Only process if the pointer
+ * value is a printable.
+ */
+ if (isprint(*(char *)bptr))
+ goto process_string;
+ }
+ }
/* fall through */
case 'd':
case 'u':
@@ -4352,6 +4372,7 @@ static struct print_arg *make_bprint_args(char *fmt, void *data, int size, struc
break;
case 's':
+ process_string:
arg = alloc_arg();
if (!arg) {
do_warning_event(event, "%s(%d): not enough memory!",
@@ -4959,6 +4980,11 @@ static void pretty_print(struct trace_seq *s, void *data, int size, struct event
if (isalnum(ptr[1]))
ptr++;
+ if (arg->type == PRINT_BSTRING) {
+ trace_seq_puts(s, arg->string.string);
+ break;
+ }
+
if (*ptr == 'F' || *ptr == 'f' ||
*ptr == 'S' || *ptr == 's') {
show_func = *ptr;