diff options
author | Steven Rostedt <[email protected]> | 2024-10-03 10:49:25 -0400 |
---|---|---|
committer | Steven Rostedt (Google) <[email protected]> | 2024-10-03 16:43:22 -0400 |
commit | 50a3242d84ee1625b0bfef29b95f935958dccfbe (patch) | |
tree | e9e58f2a66b837742b1ff8dd7d253be884df2d33 | |
parent | 9852d85ec9d492ebef56dc5f229416c925758edc (diff) |
tracing: Fix trace_check_vprintf() when tp_printk is used
When the tp_printk kernel command line is used, the trace events go
directly to printk(). It is still checked via the trace_check_vprintf()
function to make sure the pointers of the trace event are legit.
The addition of reading buffers from previous boots required adding a
delta between the addresses of the previous boot and the current boot so
that the pointers in the old buffer can still be used. But this required
adding a trace_array pointer to acquire the delta offsets.
The tp_printk code does not provide a trace_array (tr) pointer, so when
the offsets were examined, a NULL pointer dereference happened and the
kernel crashed.
If the trace_array does not exist, just default the delta offsets to zero,
as that also means the trace event is not being read from a previous boot.
Link: https://lore.kernel.org/all/[email protected]/
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Link: https://lore.kernel.org/[email protected]
Fixes: 07714b4bb3f98 ("tracing: Handle old buffer mappings for event strings and functions")
Reported-by: Alison Schofield <[email protected]>
Tested-by: Alison Schofield <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
-rw-r--r-- | kernel/trace/trace.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c01375adc471..1c69ca1f1088 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3697,8 +3697,8 @@ static void test_can_verify(void) void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, va_list ap) { - long text_delta = iter->tr->text_delta; - long data_delta = iter->tr->data_delta; + long text_delta = 0; + long data_delta = 0; const char *p = fmt; const char *str; bool good; @@ -3710,6 +3710,17 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, if (static_branch_unlikely(&trace_no_verify)) goto print; + /* + * When the kernel is booted with the tp_printk command line + * parameter, trace events go directly through to printk(). + * It also is checked by this function, but it does not + * have an associated trace_array (tr) for it. + */ + if (iter->tr) { + text_delta = iter->tr->text_delta; + data_delta = iter->tr->data_delta; + } + /* Don't bother checking when doing a ftrace_dump() */ if (iter->fmt == static_fmt_buf) goto print; |