3.16.60-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> commit bcdd0ca8cb8730573afebcaae4138f8f4c8eaa20 upstream. syzbot is reporting crashes triggered by memory allocation fault injection at tty_ldisc_get() [1]. As an attempt to handle OOM in a graceful way, we have tried commit 5362544bebe85071 ("tty: don't panic on OOM in tty_set_ldisc()"). But we reverted that attempt by commit a8983d01f9b7d600 ("Revert "tty: don't panic on OOM in tty_set_ldisc()"") due to reproducible crash. We should spend resource for finding and fixing race condition bugs rather than complicate error paths for 2 * sizeof(void *) bytes allocation failure. [1] https://syzkaller.appspot.com/bug?id=489d33fa386453859ead58ff5171d43772b13aa3 Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> Reported-by: syzbot <syzbot+40b7287c2dc987c48...@syzkaller.appspotmail.com> Cc: Michal Hocko <mho...@suse.com> Cc: Vegard Nossum <vegard.nos...@gmail.com> Cc: Dmitry Vyukov <dvyu...@google.com> Cc: Jiri Slaby <jsl...@suse.com> Cc: Peter Hurley <pe...@hurleysoftware.com> Cc: One Thousand Gnomes <gno...@lxorguk.ukuu.org.uk> Cc: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> Signed-off-by: Ben Hutchings <b...@decadent.org.uk> --- drivers/tty/tty_ldisc.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -171,12 +171,11 @@ static struct tty_ldisc *tty_ldisc_get(s return ERR_CAST(ldops); } - ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); - if (ld == NULL) { - put_ldops(ldops); - return ERR_PTR(-ENOMEM); - } - + /* + * There is no way to handle allocation failure of only 16 bytes. + * Let's simplify error handling and save more memory. + */ + ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | __GFP_NOFAIL); ld->ops = ldops; ld->tty = tty;