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Message-ID: <2b39a714cdcd4299be8c404ae699a4d3@AcuMS.aculab.com>
Date: Mon, 14 Aug 2023 15:29:46 +0000
From: David Laight <David.Laight@...LAB.COM>
To: David Laight <David.Laight@...LAB.COM>,
'Linus Torvalds' <torvalds@...ux-foundation.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Andy Shevchenko" <andriy.shevchenko@...ux.intel.com>,
Andrew Morton <akpm@...ux-foundation.org>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
Christoph Hellwig <hch@...radead.org>,
"Jason A. Donenfeld" <Jason@...c4.com>
Subject: RE: [PATCH v3 5/5] minmax: Relax check to allow comparison between
int and small unsigned constants.
From: David Laight
> Sent: 14 August 2023 15:51
>
> From: Linus Torvalds <torvalds@...ux-foundation.org>
> > Sent: 10 August 2023 20:47
> ...
> > But using an *unsigned* constant 20 when the other side is signed
> > means that now somebody is confused. We should warn.
>
> Then you get 'fixes' like:
>
> int do_tcp_getsockopt(struct sock *sk, int level,
> int optname, sockptr_t optval, sockptr_t optlen)
> {
> struct inet_connection_sock *icsk = inet_csk(sk);
> struct tcp_sock *tp = tcp_sk(sk);
> struct net *net = sock_net(sk);
> int val, len;
>
> if (copy_from_sockptr(&len, optlen, sizeof(int)))
> return -EFAULT;
>
> len = min_t(unsigned int, len, sizeof(int));
>
> if (len < 0)
> return -EINVAL;
Actually that code has been broken since the test was added in 2.4.4.
At that time min() was a local inline with unsigned int args.
2.4.9 added min(type,a,b)
2.4.10 renamed min() to min_t() and added min() with the strict
type checking.
David
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