On 01/22/2018, 09:44 AM, Greg Kroah-Hartman wrote: > 4.14-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Li Jinyue <lijinyue@xxxxxxxxxx> > > commit fbe0e839d1e22d88810f3ee3e2f1479be4c0aa4a upstream. > > UBSAN reports signed integer overflow in kernel/futex.c: > > UBSAN: Undefined behaviour in kernel/futex.c:2041:18 > signed integer overflow: > 0 - -2147483648 cannot be represented in type 'int' > > Add a sanity check to catch negative values of nr_wake and nr_requeue. > > Signed-off-by: Li Jinyue <lijinyue@xxxxxxxxxx> > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: peterz@xxxxxxxxxxxxx > Cc: dvhart@xxxxxxxxxxxxx > Link: https://lkml.kernel.org/r/1513242294-31786-1-git-send-email-lijinyue@xxxxxxxxxx > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > --- > kernel/futex.c | 3 +++ > 1 file changed, 3 insertions(+) > > --- a/kernel/futex.c > +++ b/kernel/futex.c > @@ -1878,6 +1878,9 @@ static int futex_requeue(u32 __user *uad > struct futex_q *this, *next; > DEFINE_WAKE_Q(wake_q); > > + if (nr_wake < 0 || nr_requeue < 0) > + return -EINVAL; This breaks strace's test suite on 4.14.15 (and is present in upstream obviously too): futex(0x7ff568b44ffc, 0x3, 0xfacefeed, 0xbadda7a0ca7b100d, 0x7ff568b44ffc, 0x9caffee1) = -1: Invalid argument strace uses weird values in the testkit to pass down to futex as can be seen. I think like in: commit e78c38f6bdd900b2ad9ac9df8eff58b745dc5b3c Author: Jiri Slaby <jslaby@xxxxxxx> Date: Mon Oct 23 13:41:51 2017 +0200 futex: futex_wake_op, do not fail on invalid op something similar should be done here too. Maybe: if (nr_wake < 0) nr_wake = 0; if (nr_requeue < 0) nr_requeue = 0; ? Maybe also with some pr_info_ratelimited like in the above commit? thanks, -- js suse labs