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authorSteven Rostedt (Google) <rostedt@goodmis.org>2022-07-19 18:20:04 -0400
committerSteven Rostedt (Google) <rostedt@goodmis.org>2022-07-30 13:56:09 -0400
commit3a2dcbaf4d31023106975d6ae75b6df080c454cb (patch)
tree5cd6d1d7bf7f28243a85df29d9825ab9c12c95b6 /include/trace/stages
parent9abc291812d784bd4a26c01af4ebdbf9f2dbf0bb (diff)
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/stages')
-rw-r--r--include/trace/stages/stage6_event_callback.h7
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)