path: root/src/conntrack/copy.c
diff options
authorDaniel Gröber <>2020-06-24 15:29:59 +0200
committerPablo Neira Ayuso <>2020-07-01 12:54:06 +0200
commit6c7c716bec3b3302c2212c9273c33f9640de8206 (patch)
treef6d46c7cbba64c9290e6d50312c79827a3a237ef /src/conntrack/copy.c
parent16756ca4edb55cdd8c88f4e123ffa6b94501d050 (diff)
conntrack: Replace strncpy with snprintf to improve null byte handling
We currently use strncpy in a bunch of places which has this weird quirk where it doesn't write a terminating null byte if the input string is >= the max length. To mitigate this we write a null byte to the last character manually. While this works it is easy to forget. Instead we should just be using snprintf which has more sensible behaviour as it always writes a null byte even when truncating the string. Signed-off-by: Daniel Gröber <> Signed-off-by: Pablo Neira Ayuso <>
Diffstat (limited to 'src/conntrack/copy.c')
1 files changed, 2 insertions, 2 deletions
diff --git a/src/conntrack/copy.c b/src/conntrack/copy.c
index eca202e..402f994 100644
--- a/src/conntrack/copy.c
+++ b/src/conntrack/copy.c
@@ -427,8 +427,8 @@ static void copy_attr_repl_off_aft(struct nf_conntrack *dest,
static void copy_attr_helper_name(struct nf_conntrack *dest,
const struct nf_conntrack *orig)
- strncpy(dest->helper_name, orig->helper_name, NFCT_HELPER_NAME_MAX);
- dest->helper_name[NFCT_HELPER_NAME_MAX-1] = '\0';
+ snprintf(dest->helper_name, NFCT_HELPER_NAME_MAX, "%s",
+ orig->helper_name);
static void copy_attr_zone(struct nf_conntrack *dest,