tracing: One crash fix and 3 minor fixes for v6.19

tracing fixes for v6.19:

- Fix a crash with passing a stacktrace between synthetic events

A synthetic event is an event that combines two events into a single event that can display fields from both events as well as the time delta that took place between the events. It can also pass a stacktrace from the first event so that it can be displayed by the synthetic event (this is useful to get a stacktrace of a task scheduling out when blocked and recording the time it was blocked for).

A synthetic event can also connect an existing synthetic event to another event. An issue was found that if the first synthetic event had a stacktrace as one of its fields, and that stacktrace field was passed to the new synthetic event to be displayed, it would crash the kernel. This was due to the stacktrace not being saved as a stacktrace but was still marked as one. When the stacktrace was read, it would try to read an array but instead read the integer metadata of the stacktrace and dereferenced a bad value.

Fix this by saving the stacktrace field as a stracktrace.

- Fix possible overflow in cmp_mod_entry() compare function

A binary search is used to find a module address and if the addresses are greater than 2GB apart it could lead to truncation and cause a bad search result. Use normal compares instead of a subtraction between addresses to calculate the compare value.

- Fix output of entry arguments in function graph tracer

Depending on the configurations enabled, the entry can be two different types that hold the argument array. The macro FGRAPH_ENTRY_ARGS() is used to find the correct arguments from the given type. One location was missed and still referenced the arguments directly via entry->args and could produce the wrong value depending on how the kernel was configured.

- Fix memory leak in scripts/tracepoint-update build tool

If the array fails to allocate, the memory for the values needs to be freed and was not. Free the allocated values if the array failed to allocate.

git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace/fixes

Head SHA1: 361eb853c655288f3b5c8020f6cd95d69ffe6479

Donglin Peng (1):
function_graph: Fix args pointer mismatch in print_graph_retval()

Ian Rogers (1):
tracing: Avoid possible signed 64-bit truncation

Steven Rostedt (1):
tracing: Fix crash on synthetic stacktrace field usage

Weigang He (1):
scripts/tracepoint-update: Fix memory leak in add_string() on failure

----

 kernel/trace/trace.c                 | 8 ++++----
 kernel/trace/trace_events_hist.c     | 9 +++++++++
 kernel/trace/trace_events_synth.c    | 8 +++++++-
 kernel/trace/trace_functions_graph.c | 2 +-
 scripts/tracepoint-update.c          | 2 ++
 5 files changed, 23 insertions(+), 6 deletions(-)