2019-07-09 03:14:45

by J. Bruce Fields

[permalink] [raw]
Subject: Re: [PATCH 8/8] nfsd: Fix misuse of strlcpy

On Thu, Jul 04, 2019 at 04:57:48PM -0700, Joe Perches wrote:
> Probable cut&paste typo - use the correct field size.

Huh, that's been there forever, I wonder why we haven't seen crashes?
Oh, I see, name and authname both have the same size.

Anyway, makes sense, thanks. Will apply for 5.3.

(Unless someone else is getting this; I didn't get copied on the rest of
the series.)

--b.

>
> Signed-off-by: Joe Perches <[email protected]>
> ---
> fs/nfsd/nfs4idmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/nfsd/nfs4idmap.c b/fs/nfsd/nfs4idmap.c
> index 2961016097ac..d1f285245af8 100644
> --- a/fs/nfsd/nfs4idmap.c
> +++ b/fs/nfsd/nfs4idmap.c
> @@ -83,7 +83,7 @@ ent_init(struct cache_head *cnew, struct cache_head *citm)
> new->type = itm->type;
>
> strlcpy(new->name, itm->name, sizeof(new->name));
> - strlcpy(new->authname, itm->authname, sizeof(new->name));
> + strlcpy(new->authname, itm->authname, sizeof(new->authname));
> }
>
> static void
> --
> 2.15.0


2019-07-09 05:42:00

by Joe Perches

[permalink] [raw]
Subject: Re: [PATCH 8/8] nfsd: Fix misuse of strlcpy

On Mon, 2019-07-08 at 23:14 -0400, J. Bruce Fields wrote:
> On Thu, Jul 04, 2019 at 04:57:48PM -0700, Joe Perches wrote:
> > Probable cut&paste typo - use the correct field size.
>
> Huh, that's been there forever, I wonder why we haven't seen crashes?
> Oh, I see, name and authname both have the same size.
>
> Anyway, makes sense, thanks. Will apply for 5.3.
>
> (Unless someone else is getting this; I didn't get copied on the rest of
> the series.)

It's generally hard to cc everyone on treewide fixes like this.

There's no good mechanism I know of.
vger mailing lists reject emails with too many addressees.

Do you have an opinion on adding the stracpy macro which
could avoid many of these defects?

---
include/linux/string.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h
index 4deb11f7976b..ef01bd6f19df 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -35,6 +35,22 @@ ssize_t strscpy(char *, const char *, size_t);
/* Wraps calls to strscpy()/memset(), no arch specific code required */
ssize_t strscpy_pad(char *dest, const char *src, size_t count);

+#define stracpy(to, from) \
+({ \
+ size_t size = ARRAY_SIZE(to); \
+ BUILD_BUG_ON(!__same_type(typeof(*to), char)); \
+ \
+ strscpy(to, from, size); \
+})
+
+#define stracpy_pad(to, from) \
+({ \
+ size_t size = ARRAY_SIZE(to); \
+ BUILD_BUG_ON(!__same_type(typeof(*to), char)); \
+ \
+ strscpy_pad(to, from, size); \
+})
+
#ifndef __HAVE_ARCH_STRCAT
extern char * strcat(char *, const char *);
#endif



2019-07-09 23:37:27

by J. Bruce Fields

[permalink] [raw]
Subject: Re: [PATCH 8/8] nfsd: Fix misuse of strlcpy

On Mon, Jul 08, 2019 at 10:40:50PM -0700, Joe Perches wrote:
> On Mon, 2019-07-08 at 23:14 -0400, J. Bruce Fields wrote:
> > On Thu, Jul 04, 2019 at 04:57:48PM -0700, Joe Perches wrote:
> > > Probable cut&paste typo - use the correct field size.
> >
> > Huh, that's been there forever, I wonder why we haven't seen crashes?
> > Oh, I see, name and authname both have the same size.
> >
> > Anyway, makes sense, thanks. Will apply for 5.3.
> >
> > (Unless someone else is getting this; I didn't get copied on the rest of
> > the series.)
>
> It's generally hard to cc everyone on treewide fixes like this.
>
> There's no good mechanism I know of.
> vger mailing lists reject emails with too many addressees.

Yeah. I guess what I don't understand is why this patch is part of a
series at all. It makes me wonder if there's some dependency I missed
or if the 0/8 mail actually asked somebody else to apply it.

Whatever, I guess I'm being silly, it clearly stands alone. Applying
for 5.3.

> Do you have an opinion on adding the stracpy macro which
> could avoid many of these defects?

I don't have an opinion.

--b.


> ---
> include/linux/string.h | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/include/linux/string.h b/include/linux/string.h
> index 4deb11f7976b..ef01bd6f19df 100644
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -35,6 +35,22 @@ ssize_t strscpy(char *, const char *, size_t);
> /* Wraps calls to strscpy()/memset(), no arch specific code required */
> ssize_t strscpy_pad(char *dest, const char *src, size_t count);
>
> +#define stracpy(to, from) \
> +({ \
> + size_t size = ARRAY_SIZE(to); \
> + BUILD_BUG_ON(!__same_type(typeof(*to), char)); \
> + \
> + strscpy(to, from, size); \
> +})
> +
> +#define stracpy_pad(to, from) \
> +({ \
> + size_t size = ARRAY_SIZE(to); \
> + BUILD_BUG_ON(!__same_type(typeof(*to), char)); \
> + \
> + strscpy_pad(to, from, size); \
> +})
> +
> #ifndef __HAVE_ARCH_STRCAT
> extern char * strcat(char *, const char *);
> #endif
>
>