diff mbox series

[libnl-tiny] genl_family: explicitly null terminate strncpy destination buffer

Message ID 20220523191532.22301-1-ynezz@true.cz
State Accepted
Delegated to: Petr Štetiar
Headers show
Series [libnl-tiny] genl_family: explicitly null terminate strncpy destination buffer | expand

Commit Message

Petr Štetiar May 23, 2022, 7:15 p.m. UTC 
The strncpy() function doesn't null terminate the destination string if
the source string is at least as long as the destination. (This behavior
is defined by the C99 specification.) As a result, the destination
string must be null terminated after calling strncpy().

And clang11 static analyzer thus reports following:

 genl_family.c:148:2: error: ‘strncpy’ output may be truncated copying 15 bytes from a string of length 15 [-Werror=stringop-truncation]
   148 |  strncpy(grp->name, name, GENL_NAMSIZ - 1);
       |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cc: Felix Fietkau <nbd@nbd.name>
References: https://gitlab.com/openwrt/project/libnl-tiny/-/jobs/2495301251#L197
Signed-off-by: Petr Štetiar <ynezz@true.cz>
---
 genl_family.c                 | 1 +
 include/netlink/genl/family.h | 1 +
 2 files changed, 2 insertions(+)
diff mbox series

Patch

diff --git a/genl_family.c b/genl_family.c
index 221acfa1a7ff..a0d83dc20ce8 100644
--- a/genl_family.c
+++ b/genl_family.c
@@ -146,6 +146,7 @@  int genl_family_add_grp(struct genl_family *family, uint32_t id,
 
 	grp->id = id;
 	strncpy(grp->name, name, GENL_NAMSIZ - 1);
+	grp->name[GENL_NAMSIZ - 1] = '\0';
 
 	nl_list_add_tail(&grp->list, &family->gf_mc_grps);
 
diff --git a/include/netlink/genl/family.h b/include/netlink/genl/family.h
index 8a1a38ba25d5..ca71181e89f3 100644
--- a/include/netlink/genl/family.h
+++ b/include/netlink/genl/family.h
@@ -82,6 +82,7 @@  static inline char *genl_family_get_name(struct genl_family *family)
 static inline void genl_family_set_name(struct genl_family *family, const char *name)
 {
 	strncpy(family->gf_name, name, GENL_NAMSIZ-1);
+	family->gf_name[GENL_NAMSIZ - 1] = '\0';
 	family->ce_mask |= FAMILY_ATTR_NAME;
 }