@@ -67,6 +67,7 @@
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/rcupdate.h>
+#include <linux/kallsyms.h>
#include <linux/stacktrace.h>
#include <linux/resource.h>
#include <linux/module.h>
@@ -386,17 +387,19 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
unsigned long wchan;
+ char symname[KSYM_NAME_LEN];
- if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
- wchan = get_wchan(task);
- else
- wchan = 0;
+ if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
+ goto print0;
- if (wchan)
- seq_printf(m, "%ps", (void *) wchan);
- else
- seq_putc(m, '0');
+ wchan = get_wchan(task);
+ if (wchan && !lookup_symbol_name(wchan, symname)) {
+ seq_puts(m, symname);
+ return 0;
+ }
+print0:
+ seq_putc(m, '0');
return 0;
}
#endif /* CONFIG_KALLSYMS */
This reverts commit 152c432b128cb043fc107e8f211195fe94b2159c. When a kernel address couldn't be symbolized for /proc/$pid/wchan, it would leak the raw value, a potential information exposure. This is a regression compared to the safer pre-v5.12 behavior. Reported-by: kernel test robot <oliver.sang@intel.com> Link: https://lore.kernel.org/all/20210103142726.GC30643@xsang-OptiPlex-9020/ Reported-by: Vito Caputo <vcaputo@pengaru.com> Link: https://lore.kernel.org/lkml/20210921193249.el476vlhg5k6lfcq@shells.gnugeneration.com/ Reported-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/lkml/CAG48ez2zC=+PuNgezH53HBPZ8CXU5H=vkWx7nJs60G8RXt3w0Q@mail.gmail.com/ Cc: stable@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- fs/proc/base.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)