Messages in this thread Patch in this message | | | Subject | Re: [Fwd: [PATCH 1/2] string: Add stracpy and stracpy_pad mechanisms] | From | Joe Perches <> | Date | Wed, 24 Jul 2019 03:43:22 -0700 |
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On Wed, 2019-07-24 at 10:28 +0000, David Laight wrote: > From: Joe Perches > > Sent: 24 July 2019 05:38 > > On Tue, 2019-07-23 at 23:27 -0500, Julia Lawall wrote: > > > On Tue, 23 Jul 2019, Joe Perches wrote: > > > > On Tue, 2019-07-23 at 22:54 -0500, Julia Lawall wrote: > > > > > A seantic patch and the resulting output for the case where the third > > > > > arugument is a constant is attached. Likewise the resulting output on a > > > > > recent linux-next. [] > > > > There is a problem with conversions with assignments > > > > of strlcpy() so ideally the cocci script should make sure > > > > any return value was not used before conversion. > > > > > > > > This is not a provably good conversion: > > > > > > > > drivers/s390/char/sclp_ftp.c > > > > @@ -114,8 +114,7 @@ static int sclp_ftp_et7(const struct hmc > > > > sccb->evbuf.mdd.ftp.length = ftp->len; > > > > sccb->evbuf.mdd.ftp.bufaddr = virt_to_phys(ftp->buf); > > > > > > > > - len = strlcpy(sccb->evbuf.mdd.ftp.fident, ftp->fname, > > > > - HMCDRV_FTP_FIDENT_MAX); > > > > + len = stracpy(sccb->evbuf.mdd.ftp.fident, ftp->fname); [] > > Any use of the strlcpy return value should not be converted > > because the logic after an assignment or use of the return value > > can not be assured to have the same behavior. > > Most of the code probably expects the length to be that copied > (so is broken if the string is truncated).
Fortunately there are relatively few uses of the return value of strlcpy so it's not a large problem set.
Slightly unrepresentative counts:
$ git grep -P "^\s+strlcpy\b" | wc -l 1681 $ git grep -P "=\s*strlcpy\b" | wc -l 28
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