Messages in this thread | | | Date | Wed, 17 Jun 2020 22:27:43 +0200 (CEST) | From | Julia Lawall <> | Subject | Re: [Cocci] [PATCH] coccinelle: api: add device_attr_show script |
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On Mon, 15 Jun 2020, Denis Efremov wrote:
> According to the documentation[1] show() methods of device attributes > should return the number of bytes printed into the buffer. This is > the return value of scnprintf(). show() must not use snprintf() > when formatting the value to be returned to user space. snprintf() > returns the length the resulting string would be, assuming it all > fit into the destination array[2]. scnprintf() return the length of > the string actually created in buf. If one can guarantee that an > overflow will never happen sprintf() can be used otherwise scnprintf().
The semantic patch looks fine. Do you have any accepted patches from this?
julia
> > [1] Documentation/filesystems/sysfs.txt > [2] "snprintf() confusion" https://lwn.net/Articles/69419/ > > Signed-off-by: Denis Efremov <efremov@linux.com> > --- > scripts/coccinelle/api/device_attr_show.cocci | 55 +++++++++++++++++++ > 1 file changed, 55 insertions(+) > create mode 100644 scripts/coccinelle/api/device_attr_show.cocci > > diff --git a/scripts/coccinelle/api/device_attr_show.cocci b/scripts/coccinelle/api/device_attr_show.cocci > new file mode 100644 > index 000000000000..d8ec4bb8ac41 > --- /dev/null > +++ b/scripts/coccinelle/api/device_attr_show.cocci > @@ -0,0 +1,55 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/// > +/// From Documentation/filesystems/sysfs.txt: > +/// show() must not use snprintf() when formatting the value to be > +/// returned to user space. If you can guarantee that an overflow > +/// will never happen you can use sprintf() otherwise you must use > +/// scnprintf(). > +/// > +// Confidence: High > +// Copyright: (C) 2020 Denis Efremov ISPRAS > +// Options: --no-includes --include-headers > +// > + > +virtual report > +virtual org > +virtual context > +virtual patch > + > +@r depends on !patch@ > +identifier show, dev, attr, buf; > +position p; > +@@ > + > +ssize_t show(struct device *dev, struct device_attribute *attr, char *buf) > +{ > + <... > +* return snprintf@p(...); > + ...> > +} > + > +@rp depends on patch@ > +identifier show, dev, attr, buf; > +@@ > + > +ssize_t show(struct device *dev, struct device_attribute *attr, char *buf) > +{ > + <... > + return > +- snprintf > ++ scnprintf > + (...); > + ...> > +} > + > +@script: python depends on report@ > +p << r.p; > +@@ > + > +coccilib.report.print_report(p[0], "WARNING: use scnprintf or sprintf") > + > +@script: python depends on org@ > +p << r.p; > +@@ > + > +coccilib.org.print_todo(p[0], "WARNING: use scnprintf or sprintf") > -- > 2.26.2 > > _______________________________________________ > Cocci mailing list > Cocci@systeme.lip6.fr > https://systeme.lip6.fr/mailman/listinfo/cocci >
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