From: Andy Lutomirski <[email protected]>
commit 0a1eb2d474edfe75466be6b4677ad84e5e8ca3f5 upstream.
Reporting these fields on a non-current task is dangerous. If the
task is in any state other than normal kernel code, they may contain
garbage or even kernel addresses on some architectures. (x86_64
used to do this. I bet lots of architectures still do.) With
CONFIG_THREAD_INFO_IN_TASK=y, it can OOPS, too.
As far as I know, there are no use programs that make any material
use of these fields, so just get rid of them.
Reported-by: Jann Horn <[email protected]>
Signed-off-by: Andy Lutomirski <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Linux API <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Tycho Andersen <[email protected]>
Link: http://lkml.kernel.org/r/a5fed4c3f4e33ed25d4bb03567e329bc5a712bcc.1475257877.git.luto@kernel.org
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: zhangyi (F) <[email protected]>
---
fs/proc/array.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 60cbaa821164..618c83f1866d 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -425,10 +425,11 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
mm = get_task_mm(task);
if (mm) {
vsize = task_vsize(mm);
- if (permitted) {
- eip = KSTK_EIP(task);
- esp = KSTK_ESP(task);
- }
+ /*
+ * esp and eip are intentionally zeroed out. There is no
+ * non-racy way to read them without freezing the task.
+ * Programs that need reliable values can use ptrace(2).
+ */
}
get_task_comm(tcomm, task);
--
2.17.2