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| author |   Steven Rostedt (Google) <rostedt@goodmis.org> | 2022-07-19 18:20:04 -0400 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2022-07-30 13:56:09 -0400 |
| commit | 3a2dcbaf4d31023106975d6ae75b6df080c454cb (patch) | |
| tree | 5cd6d1d7bf7f28243a85df29d9825ab9c12c95b6 /include/trace | |
| parent | batman-adv: tracing: Use the new __vstring() helper (diff) | |
| download | linux-dev-3a2dcbaf4d31023106975d6ae75b6df080c454cb.tar.xz linux-dev-3a2dcbaf4d31023106975d6ae75b6df080c454cb.zip | |
tracing: Use a copy of the va_list for __assign_vstr()
If an instance of tracing enables the same trace event as another
instance, or the top level instance, or even perf, then the va_list passed
into some tracepoints can be used more than once.
As va_list can only be traversed once, this can cause issues:
# cat /sys/kernel/tracing/instances/qla2xxx/trace
cat-56106 [012] ..... 2419873.470098: ql_dbg_log: qla2xxx [0000:05:00.0]-1054:14: Entered (null).
cat-56106 [012] ..... 2419873.470101: ql_dbg_log: qla2xxx [0000:05:00.0]-1000:14: Entered ×+<96>²Ü<98>^H.
cat-56106 [012] ..... 2419873.470102: ql_dbg_log: qla2xxx [0000:05:00.0]-1006:14: Prepare to issue mbox cmd=0xde589000.
# cat /sys/kernel/tracing/trace
cat-56106 [012] ..... 2419873.470097: ql_dbg_log: qla2xxx [0000:05:00.0]-1054:14: Entered qla2x00_get_firmware_state.
cat-56106 [012] ..... 2419873.470100: ql_dbg_log: qla2xxx [0000:05:00.0]-1000:14: Entered qla2x00_mailbox_command.
cat-56106 [012] ..... 2419873.470102: ql_dbg_log: qla2xxx [0000:05:00.0]-1006:14: Prepare to issue mbox cmd=0x69.
The instance version is corrupted because the top level instance iterated
the va_list first.
Use va_copy() in the __assign_vstr() macro to make sure that each trace
event for each use case gets a fresh va_list.
Link: https://lore.kernel.org/all/259d53a5-958e-6508-4e45-74dba2821242@marvell.com/
Link: https://lkml.kernel.org/r/20220719182004.21daa83e@gandalf.local.home
Fixes: 0563231f93c6d ("tracing/events: Add __vstring() and __assign_vstr() helper macros")
Reported-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'include/trace')
| -rw-r--r-- | include/trace/stages/stage6_event_callback.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/include/trace/stages/stage6_event_callback.h b/include/trace/stages/stage6_event_callback.h index 0f51f6b3ab70..3c554a585320 100644 --- a/include/trace/stages/stage6_event_callback.h +++ b/include/trace/stages/stage6_event_callback.h @@ -40,7 +40,12 @@ #undef __assign_vstr #define __assign_vstr(dst, fmt, va) \ - vsnprintf(__get_str(dst), TRACE_EVENT_STR_MAX, fmt, *(va)) + do { \ + va_list __cp_va; \ + va_copy(__cp_va, *(va)); \ + vsnprintf(__get_str(dst), TRACE_EVENT_STR_MAX, fmt, __cp_va); \ + va_end(__cp_va); \ + } while (0) #undef __bitmask #define __bitmask(item, nr_bits) __dynamic_array(unsigned long, item, -1) |