5.4-stable review patch. If anyone has any objections, please let me know.
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From: Steven Rostedt (Google) rostedt@goodmis.org
[ Upstream commit 5efd3e2aef91d2d812290dcb25b2058e6f3f532c ]
This reverts 60be76eeabb3d ("tracing: Add size check when printing trace_marker output"). The only reason the precision check was added was because of a bug that miscalculated the write size of the string into the ring buffer and it truncated it removing the terminating nul byte. On reading the trace it crashed the kernel. But this was due to the bug in the code that happened during development and should never happen in practice. If anything, the precision can hide bugs where the string in the ring buffer isn't nul terminated and it will not be checked.
Link: https://lore.kernel.org/all/C7E7AF1A-D30F-4D18-B8E5-AF1EF58004F5@linux.ibm.c... Link: https://lore.kernel.org/linux-trace-kernel/20240227125706.04279ac2@gandalf.l... Link: https://lore.kernel.org/all/20240302111244.3a1674be@gandalf.local.home/ Link: https://lore.kernel.org/linux-trace-kernel/20240304174341.2a561d9f@gandalf.l...
Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Linus Torvalds torvalds@linux-foundation.org Fixes: 60be76eeabb3d ("tracing: Add size check when printing trace_marker output") Reported-by: Sachin Sant sachinp@linux.ibm.com Tested-by: Sachin Sant sachinp@linux.ibm.com Reviewed-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/trace/trace_output.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index 9ffe54ff3edb2..b194dd1c8420f 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -1291,12 +1291,11 @@ static enum print_line_t trace_print_print(struct trace_iterator *iter, { struct print_entry *field; struct trace_seq *s = &iter->seq; - int max = iter->ent_size - offsetof(struct print_entry, buf);
trace_assign_type(field, iter->ent);
seq_print_ip_sym(s, field->ip, flags); - trace_seq_printf(s, ": %.*s", max, field->buf); + trace_seq_printf(s, ": %s", field->buf);
return trace_handle_return(s); } @@ -1305,11 +1304,10 @@ static enum print_line_t trace_print_raw(struct trace_iterator *iter, int flags, struct trace_event *event) { struct print_entry *field; - int max = iter->ent_size - offsetof(struct print_entry, buf);
trace_assign_type(field, iter->ent);
- trace_seq_printf(&iter->seq, "# %lx %.*s", field->ip, max, field->buf); + trace_seq_printf(&iter->seq, "# %lx %s", field->ip, field->buf);
return trace_handle_return(&iter->seq); }