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linux/include/trace/stages
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Steven Rostedt (Google) 4ee7e7dd1f tracing: Use a copy of the va_list for __assign_vstr() 
commit 3a2dcbaf4d upstream.

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: 0563231f93 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2022-08-17 15:16:20 +02:00
..
init.h tracing: Move the defines to create TRACE_EVENTS into their own files 2022-03-11 11:49:23 -05:00
stage1_struct_define.h tracing/events: Add __vstring() and __assign_vstr() helper macros 2022-08-17 15:16:09 +02:00
stage2_data_offsets.h tracing/events: Add __vstring() and __assign_vstr() helper macros 2022-08-17 15:16:09 +02:00
stage3_trace_output.h tracing: Rename the staging files for trace_events 2022-04-02 08:40:04 -04:00
stage4_event_fields.h tracing: Use a struct alignof to determine trace event field alignment 2022-08-17 15:16:15 +02:00
stage5_get_offsets.h tracing/events: Add __vstring() and __assign_vstr() helper macros 2022-08-17 15:16:09 +02:00
stage6_event_callback.h tracing: Use a copy of the va_list for __assign_vstr() 2022-08-17 15:16:20 +02:00
stage7_class_define.h tracing: Rename the staging files for trace_events 2022-04-02 08:40:04 -04:00