| Message ID | 20210323125535.1866249-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block/rnbd-clt: fix overlapping snprintf arguments | expand |
On Tue, Mar 23, 2021 at 1:55 PM Arnd Bergmann <arnd@kernel.org> wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > The -Wrestrict warning (disabled by default) points out undefined > behavior calling snprintf(): > > drivers/block/rnbd/rnbd-clt-sysfs.c: In function 'rnbd_clt_get_path_name': > drivers/block/rnbd/rnbd-clt-sysfs.c:486:8: error: 'snprintf' argument 4 overlaps destination object 'buf' [-Werror=restrict] > 486 | ret = snprintf(buf, len, "%s@%s", buf, dev->sess->sessname); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/block/rnbd/rnbd-clt-sysfs.c:472:67: note: destination object referenced by 'restrict'-qualified argument 1 was declared here > 472 | static int rnbd_clt_get_path_name(struct rnbd_clt_dev *dev, char *buf, > | ~~~~~~^~~ > > This can be simplified by using a single snprintf() to print the > whole buffer, avoiding the undefined behavior. > > Fixes: 91f4acb2801c ("block/rnbd-clt: support mapping two devices with the same name from different servers") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/block/rnbd/rnbd-clt-sysfs.c | 6 +----- > 1 file changed, 1 insertion(+), 5 deletions(-) > > diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c > index d4aa6bfc9555..38251b749664 100644 > --- a/drivers/block/rnbd/rnbd-clt-sysfs.c > +++ b/drivers/block/rnbd/rnbd-clt-sysfs.c > @@ -479,11 +479,7 @@ static int rnbd_clt_get_path_name(struct rnbd_clt_dev *dev, char *buf, > while ((s = strchr(pathname, '/'))) > s[0] = '!'; > > - ret = snprintf(buf, len, "%s", pathname); > - if (ret >= len) > - return -ENAMETOOLONG; > - > - ret = snprintf(buf, len, "%s@%s", buf, dev->sess->sessname); > + ret = snprintf(buf, len, "%s@%s", pathname, dev->sess->sessname); > if (ret >= len) > return -ENAMETOOLONG; > > -- > 2.29.2 > Thanks Arnd, We have a same patch will send out soon as part of a bigger patchset.
diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c index d4aa6bfc9555..38251b749664 100644 --- a/drivers/block/rnbd/rnbd-clt-sysfs.c +++ b/drivers/block/rnbd/rnbd-clt-sysfs.c @@ -479,11 +479,7 @@ static int rnbd_clt_get_path_name(struct rnbd_clt_dev *dev, char *buf, while ((s = strchr(pathname, '/'))) s[0] = '!'; - ret = snprintf(buf, len, "%s", pathname); - if (ret >= len) - return -ENAMETOOLONG; - - ret = snprintf(buf, len, "%s@%s", buf, dev->sess->sessname); + ret = snprintf(buf, len, "%s@%s", pathname, dev->sess->sessname); if (ret >= len) return -ENAMETOOLONG;