linux-kernel - Re: [PATCH] coccinelle: api: add sprintf() support to device_attr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:   Fri, 14 Aug 2020 11:50:35 +0300
From:   Denis Efremov <efremov@...ux.com>
To:     Markus Elfring <Markus.Elfring@....de>,
        Julia Lawall <julia.lawall@...ia.fr>
Cc:     Coccinelle <cocci@...teme.lip6.fr>, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] coccinelle: api: add sprintf() support to
 device_attr_show

Hi,

Markus, I think that CCing new people and spam them with mails they
are obviously not interested in doesn't bring an additional value to
the discussion. linux-kernel and cocci mailing lists are enough
in my opinion. This also will allow us to keep "threaded" mail
order.

On 8/14/20 11:30 AM, Markus Elfring wrote:
>> Interesting enough that with this patch coccinelle starts to skip
>> patch generation in some cases. For example, it skips patch for
>> drivers/base/core.c This is an unexpected result for me.
> 
> Would you like to point questionable differences for such patch hunks out?

Without this patch the script generates:
$ spatch -D patch --no-includes --include-headers --cocci-file scripts/coccinelle/api/device_attr_show.cocci drivers/base/core.c
--- drivers/base/core.c
+++ /tmp/cocci-output-63510-2f17ff-core.c
@@ -1713,7 +1713,7 @@ ssize_t device_show_ulong(struct device
char *buf)
{
struct dev_ext_attribute *ea = to_ext_attr(attr);
-       return snprintf(buf, PAGE_SIZE, "%lx\n", *(unsigned long *)(ea->var));
+       return scnprintf(buf, PAGE_SIZE, "%lx\n", *(unsigned long *)(ea->var));
}
EXPORT_SYMBOL_GPL(device_show_ulong);

@@ -1743,7 +1743,7 @@ ssize_t device_show_int(struct device *d
{
struct dev_ext_attribute *ea = to_ext_attr(attr);

-       return snprintf(buf, PAGE_SIZE, "%d\n", *(int *)(ea->var));
+       return scnprintf(buf, PAGE_SIZE, "%d\n", *(int *)(ea->var));
}
EXPORT_SYMBOL_GPL(device_show_int);

@@ -1764,7 +1764,7 @@ ssize_t device_show_bool(struct device *
{
struct dev_ext_attribute *ea = to_ext_attr(attr);

-       return snprintf(buf, PAGE_SIZE, "%d\n", *(bool *)(ea->var));
+       return scnprintf(buf, PAGE_SIZE, "%d\n", *(bool *)(ea->var));
}
EXPORT_SYMBOL_GPL(device_show_bool);

With this patch it generates nothing. I would expect spatch to generate
a different patch with sprintf instead of scnprintf, because I think 
... is enough to match "*(int *)(ea->var)". Even if it can't match sprintf
pattern it should fallback to scnprintf pattern.

> You propose to use a nested SmPL disjunction for desired adjustments.
> I suggest to start a corresponding case distinction behind
> the key word “return” instead of repeating it three times.

It doesn't work.

Thanks,
Denis