4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jann Horn <jannh@xxxxxxxxxx>
commit 0a0b98734479aa5b3c671d5190e86273372cab95 upstream.
Commit 3a4d44b61625 ("ntp: Move adjtimex related compat syscalls to
native counterparts") removed the memset() in compat_get_timex(). Since
then, the compat adjtimex syscall can invoke do_adjtimex() with an
uninitialized ->tai.
If do_adjtimex() doesn't write to ->tai (e.g. because the arguments are
invalid), compat_put_timex() then copies the uninitialized ->tai field
to userspace.
Fix it by adding the memset() back.
Fixes: 3a4d44b61625 ("ntp: Move adjtimex related compat syscalls to native counterparts")
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/compat.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -34,6 +34,7 @@ int compat_get_timex(struct timex *txc,
{
struct compat_timex tx32;
+ memset(txc, 0, sizeof(struct timex));
if (copy_from_user(&tx32, utp, sizeof(struct compat_timex)))
return -EFAULT;
