From: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> commit 499f12168aebd6da8fa32c9b7d6203ca9b5eb88d upstream. 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@xxxxxxxxxxxxxxxx/ Cc: stable@xxxxxxxxxxxxxxx Fixes: 5013f454a352c ("tracing: Add check of trace event print fmts for dereferencing pointers") Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/trace/trace_events.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -392,12 +392,6 @@ static void test_event_printk(struct tra if (!(dereference_flags & (1ULL << arg))) goto next_arg; - /* Check for __get_sockaddr */; - if (str_has_prefix(fmt + i, "__get_sockaddr(")) { - dereference_flags &= ~(1ULL << arg); - goto next_arg; - } - /* Find the REC-> in the argument */ c = strchr(fmt + i, ','); r = strstr(fmt + i, "REC->"); @@ -413,7 +407,14 @@ static void test_event_printk(struct tra 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++;
