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-rw-r--r--fs/proc/array.c16
-rw-r--r--fs/proc/base.c9
2 files changed, 17 insertions, 8 deletions
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);
diff --git a/fs/proc/base.c b/fs/proc/base.c
index b25eee4cead5..29595af32866 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -430,13 +430,10 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
wchan = get_wchan(task);
- if (lookup_symbol_name(wchan, symname) < 0) {
- if (!ptrace_may_access(task, PTRACE_MODE_READ))
- return 0;
- seq_printf(m, "%lu", wchan);
- } else {
+ if (wchan && ptrace_may_access(task, PTRACE_MODE_READ) && !lookup_symbol_name(wchan, symname))
seq_printf(m, "%s", symname);
- }
+ else
+ seq_putc(m, '0');
return 0;
}