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| author | Steven Rostedt <rostedt@goodmis.org> | 2024-12-31 00:06:46 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-01-09 13:33:32 +0100 |
| commit | 92bd18c74624e5eb9f96e70076aa46293f4b626f (patch) | |
| tree | ca85b5ea05e23d69897ca1eb11006852239a2bbd /kernel/trace | |
| parent | cba9d51794ecde58a21e4e96bcfd0a18f7dd4ff8 (diff) | |
| download | linux-92bd18c74624e5eb9f96e70076aa46293f4b626f.tar.gz linux-92bd18c74624e5eb9f96e70076aa46293f4b626f.tar.bz2 linux-92bd18c74624e5eb9f96e70076aa46293f4b626f.zip | |
tracing: Have process_string() also allow arrays
commit afc6717628f959941d7b33728570568b4af1c4b8 upstream.
In order to catch a common bug where a TRACE_EVENT() TP_fast_assign()
assigns an address of an allocated string to the ring buffer and then
references it in TP_printk(), which can be executed hours later when the
string is free, the function test_event_printk() runs on all events as
they are registered to make sure there's no unwanted dereferencing.
It calls process_string() to handle cases in TP_printk() format that has
"%s". It returns whether or not the string is safe. But it can have some
false positives.
For instance, xe_bo_move() has:
TP_printk("move_lacks_source:%s, migrate object %p [size %zu] from %s to %s device_id:%s",
__entry->move_lacks_source ? "yes" : "no", __entry->bo, __entry->size,
xe_mem_type_to_name[__entry->old_placement],
xe_mem_type_to_name[__entry->new_placement], __get_str(device_id))
Where the "%s" references into xe_mem_type_to_name[]. This is an array of
pointers that should be safe for the event to access. Instead of flagging
this as a bad reference, if a reference points to an array, where the
record field is the index, consider it safe.
Link: https://lore.kernel.org/all/9dee19b6185d325d0e6fa5f7cbba81d007d99166.camel@sapience.com/
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20241231000646.324fb5f7@gandalf.local.home
Fixes: 65a25d9f7ac02 ("tracing: Add "%s" check in test_event_printk()")
Reported-by: Genes Lists <lists@sapience.com>
Tested-by: Gene C <arch@sapience.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace_events.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 7149cd6fd479..ea9b44847ce6 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -365,6 +365,18 @@ static bool process_string(const char *fmt, int len, struct trace_event_call *ca } while (s < e); /* + * Check for arrays. If the argument has: foo[REC->val] + * then it is very likely that foo is an array of strings + * that are safe to use. + */ + r = strstr(s, "["); + if (r && r < e) { + r = strstr(r, "REC->"); + if (r && r < e) + return true; + } + + /* * If there's any strings in the argument consider this arg OK as it * could be: REC->field ? "foo" : "bar" and we don't want to get into * verifying that logic here. |