3.16.60-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Tetsuo Handa <[email protected]> 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 <[email protected]> Reported-by: syzbot <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Vegard Nossum <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Jiri Slaby <[email protected]> Cc: Peter Hurley <[email protected]> Cc: One Thousand Gnomes <[email protected]> Cc: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> --- 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;
