X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=fs%2Fproc%2Farray.c;h=eed2050db9be9c7795acd2153f976d4742e2fe82;hb=326c2597a3b93b8a89e0c3a2b41fd9971d095a97;hp=f60f0121e3319ec616d0a0151d3e4df146637c88;hpb=16651fc2f30dfe14dcdd59cf0ccb4e1ccdba4dc7;p=firefly-linux-kernel-4.4.55.git

diff --git a/fs/proc/array.c b/fs/proc/array.c
index f60f0121e331..eed2050db9be 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -375,7 +375,7 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
 static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 			struct pid *pid, struct task_struct *task, int whole)
 {
-	unsigned long vsize, eip, esp, wchan = ~0UL;
+	unsigned long vsize, eip, esp, wchan = 0;
 	int priority, nice;
 	int tty_pgrp = -1, tty_nr = 0;
 	sigset_t sigign, sigcatch;
@@ -507,7 +507,19 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 	seq_put_decimal_ull(m, ' ', task->blocked.sig[0] & 0x7fffffffUL);
 	seq_put_decimal_ull(m, ' ', sigign.sig[0] & 0x7fffffffUL);
 	seq_put_decimal_ull(m, ' ', sigcatch.sig[0] & 0x7fffffffUL);
-	seq_put_decimal_ull(m, ' ', wchan);
+
+	/*
+	 * We used to output the absolute kernel address, but that's an
+	 * information leak - so instead we show a 0/1 flag here, to signal
+	 * to user-space whether there's a wchan field in /proc/PID/wchan.
+	 *
+	 * This works with older implementations of procps as well.
+	 */
+	if (wchan)
+		seq_puts(m, " 1");
+	else
+		seq_puts(m, " 0");
+
 	seq_put_decimal_ull(m, ' ', 0);
 	seq_put_decimal_ull(m, ' ', 0);
 	seq_put_decimal_ll(m, ' ', task->exit_signal);