On Mon, 17 May 2021 19:21:04 -0400
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> On Mon, 17 May 2021 17:21:33 +0300
> "Yordan Karadzhov (VMware)" <y.karadz@xxxxxxxxx> wrote:
>
> > v2 changes:
> > - Still showing all CPU plots from the new trace file when
> > appending [PATCH kernel-shark: Preserve open graphs when
> > appending data].
> > - Setting "seq.buffer" to NULL after calling trace_seq_destroy()
> > in [PATCH kernel-shark: Fix the checking if "trace_seq" was destroyed]
> > - [PATCH kernel-shark: No slash at the end of KS_PLUGIN_INSTALL_PREFIX]
> > is new.
>
> Hi Yordan,
>
> I was playing a bit with kernelshark, and found that if I load a file and
> append one, exit, load them again, then click:
>
> File -> Sessions -> Restore Last Session
>
> It crashes.
>
> Looks to be something is freed and then reused, because when I ran it under
> gdb, it crashed in allocation of memory (asprintf). That usually means that
> something was freed twice, someplace else. Or freed and then used.
>
Running valgrind, reported this:
==6862== Invalid read of size 8
==6862== at 0x494CA89: map_collection_back_request (libkshark-collection.c:474)
static int
map_collection_back_request(const struct kshark_entry_collection *col,
struct kshark_entry_request *req)
{
size_t req_first, req_end;
ssize_t col_index;
int req_count;
col_index = map_collection_request_init(col, req, false, &req_end);
if (col_index == KS_EMPTY_BIN)
return 0;
/*
* Now loop over the intervals of the collection going backwards till
* the end of the inputted request and create a separate request for
* each of those interest.
*/
req_count = 1;
while (col_index >= 0 && req_end <= col->break_points[col_index]) {
// col_index can be zero entering this loop.
if (req_end >= col->resume_points[col_index]) {
/*
* The last entry of the original request is inside
* the "col_index" collection interval. Close the
* collection request here and return.
*/
req->n = req->first - req_end + 1;
break;
}
/*
* The last entry of the original request is outside of the
* "col_index" interval. Close the collection request at the
* end of this interval and move to the next one. Try to make
* another request there.
*/
req->n = req->first -
col->resume_points[col_index] + 1;
--col_index;
// col_index is decremented (-1)
if (req_end > col->break_points[col_index]) {
Reading a negative index in an array.
Which is where valgrind reported. But I don't think this is what caused the
crash.
-- Steve
|