From: Dan Carpenter <dan.carpenter@oracle.com>
To: Nigel Christian <nigel.l.christian@gmail.com>
Cc: kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] mm: hugetlb: checking for IS_ERR() instead of NULL
Date: Tue, 1 Jun 2021 22:51:23 +0300 [thread overview]
Message-ID: <20210601193419.GH24442@kadam> (raw)
In-Reply-To: <20210601190040.GG24442@kadam>
Here is my next attempt at this check.
Back in 2009, I used to write Smatch checks which were too complicated.
Ideally, each Smatch check should only print one warning. The state
engine should only have one custom state, and &undefined and &merged.
That check I sent violated all those rules.
The other thing which might be interesting is if you pass a NULL
to IS_ERR() and then dereference the NULL then print a warning about
that. This has a lot of overlaps with some of my existing checks, but
it's still a new idea so it belongs in a separate check. It's fine and
good even if one bug triggers a lot of different warnings. I'll write
that, hang on, brb.
regards,
dan carpenter
/*
* Copyright (C) 2021 Oracle.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
*/
#include "smatch.h"
#include "smatch_extra.h"
static int my_id;
static void match_is_err(const char *fn, struct expression *expr, void *unused)
{
struct expression *arg, *call;
struct range_list *rl;
char *name;
arg = get_argument_from_call_expr(expr->args, 0);
/* ignore unknown values */
if (!get_implied_rl(arg, &rl))
return;
/* error pointers are what we expect */
if (rl_max(rl).uvalue >= (unsigned long long)-4095)
return;
/* ignore valid pointers */
if (rl_min(rl).uvalue != 0)
return;
/*
* Don't warn if people are using IS_ERR() to sanity check their
* parameters.
*/
call = get_assigned_expr(arg);
call = strip_expr(call);
if (!call || call->type != EXPR_CALL)
return;
name = expr_to_str(arg);
sm_warning("'%s' is not an error pointer", name);
free_string(name);
}
void check_not_an_err_ptr(int id)
{
my_id = id;
if (option_project != PROJ_KERNEL)
return;
add_function_hook("IS_ERR", &match_is_err, NULL);
}
next prev parent reply other threads:[~2021-06-01 19:51 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-01 9:25 [PATCH] mm: hugetlb: checking for IS_ERR() instead of NULL Dan Carpenter
2021-06-01 10:52 ` Mina Almasry
2021-06-01 17:54 ` Nigel Christian
2021-06-01 19:00 ` Dan Carpenter
2021-06-01 19:51 ` Dan Carpenter [this message]
2021-06-01 20:50 ` Dan Carpenter
2021-06-01 21:23 ` Nigel Christian
2021-06-02 6:11 ` Dan Carpenter
2021-06-02 14:47 ` Dan Carpenter
2021-06-02 16:01 ` Nigel Christian
2021-06-04 13:34 ` Dan Carpenter
2021-06-04 14:14 ` Nigel Christian
2021-06-04 14:21 ` Dan Carpenter
2021-06-02 14:22 ` Dan Carpenter
2021-06-02 15:57 ` Nigel Christian
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