tracing: Avoid possible signed 64-bit truncation

64-bit truncation to 32-bit can result in the sign of the truncated
value changing. The cmp_mod_entry is used in bsearch and so the
truncation could result in an invalid search order. This would only
happen were the addresses more than 2GB apart and so unlikely, but
let's fix the potentially broken compare anyway.

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260108002625.333331-1-irogers@google.com
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index baec63134ab627d2e8c03d23b087746317cf2c42..8bd4ec08fb361a3b349d0114b4ed0e0fef2b4ee1 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6115,10 +6115,10 @@ static int cmp_mod_entry(const void *key, const void *pivot)
        unsigned long addr = (unsigned long)key;
        const struct trace_mod_entry *ent = pivot;
 
-       if (addr >= ent[0].mod_addr && addr < ent[1].mod_addr)
-               return 0;
-       else
-               return addr - ent->mod_addr;
+       if (addr < ent[0].mod_addr)
+               return -1;
+
+       return addr >= ent[1].mod_addr;
 }
 
 /**