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SubjectRe: [PATCH v3] lib/string.c: implement stpcpy
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On Wed, 2020-08-26 at 16:38 -0700, Kees Cook wrote:
> On Thu, Aug 27, 2020 at 07:59:45AM +0900, Masahiro Yamada wrote:
[]
> > OK, then stpcpy(), strcpy() and sprintf()
> > have the same level of unsafety.
>
> Yes. And even snprintf() is dangerous because its return value is how
> much it WOULD have written, which when (commonly) used as an offset for
> further pointer writes, causes OOB writes too. :(
> https://github.com/KSPP/linux/issues/105
>
> > strcpy() is used everywhere.
>
> Yes. It's very frustrating, but it's not an excuse to continue
> using it nor introducing more bad APIs.
>
> $ git grep '\bstrcpy\b' | wc -l
> 2212
> $ git grep '\bstrncpy\b' | wc -l
> 751
> $ git grep '\bstrlcpy\b' | wc -l
> 1712
>
> $ git grep '\bstrscpy\b' | wc -l
> 1066
>
> https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy
> https://github.com/KSPP/linux/issues/88
>
> https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
> https://github.com/KSPP/linux/issues/89
>
> https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> https://github.com/KSPP/linux/issues/90
>
> We have no way right now to block the addition of deprecated API usage,
> which makes ever catching up on this replacement very challenging.

These could be added to checkpatch's deprecated_api test.
---
scripts/checkpatch.pl | 3 +++
1 file changed, 3 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 149518d2a6a7..f9ccb2a63a95 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -605,6 +605,9 @@ foreach my $entry (@mode_permission_funcs) {
$mode_perms_search = "(?:${mode_perms_search})";

our %deprecated_apis = (
+ "strcpy" => "strscpy",
+ "strncpy" => "strscpy",
+ "strlcpy" => "strscpy",
"synchronize_rcu_bh" => "synchronize_rcu",
"synchronize_rcu_bh_expedited" => "synchronize_rcu_expedited",
"call_rcu_bh" => "call_rcu",

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