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tracing: Have event format check not flag %p* on __get_dynamic_array() 

[ Upstream commit 499f12168a ]

The print fmt check against trace events to make sure that the format does
not use pointers that may be freed from the time of the trace to the time
the event is read, gives a false positive on %pISpc when reading data that
was saved in __get_dynamic_array() when it is perfectly fine to do so, as
the data being read is on the ring buffer.

Link: https://lore.kernel.org/all/20220407144524.2a592ed6@canb.auug.org.au/

Cc: stable@vger.kernel.org
Fixes: 5013f454a3 ("tracing: Add check of trace event print fmts for dereferencing pointers")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Steven Rostedt (Google) 2022-04-07 14:56:32 -04:00 committed by Greg Kroah-Hartman
parent 621c1d8c1b
commit 6107b01416
1 changed files with 7 additions and 0 deletions
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7
kernel/trace/trace_events.c
View File

@ -407,7 +407,14 @@ static void test_event_printk(struct trace_event_call *call)
a = strchr(fmt + i, '&');
if ((a && (a < r)) || test_field(r, call))
dereference_flags &= ~(1ULL << arg);
} else if ((r = strstr(fmt + i, "__get_dynamic_array(")) &&
(!c || r < c)) {
dereference_flags &= ~(1ULL << arg);
} else if ((r = strstr(fmt + i, "__get_sockaddr(")) &&
(!c || r < c)) {
dereference_flags &= ~(1ULL << arg);
}
next_arg:
i--;
arg++;