| Message ID | 20170725005508.30587-1-marcos.souza.org@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | Florian Westphal |
| Headers | show |
Marcos Paulo de Souza <marcos.souza.org@gmail.com> wrote: > [marcos@Icarus ~]$ conntrack -l something > nfct_labelmap_new: No such file or directory > Segmentation fault (core dumped) conntrack should not pass NULL in the first place. However I agree that lnf-conntrack should be more robust so I applied this patch, thanks. > This is my first patch to netfilter and conntrack-tools, so please let > me know if I sent to the right place, or if the patch needs more work. I changed patch title to 'labels: don't crash on NULL labelmap'. > int __labelmap_get_bit(struct nfct_labelmap *m, const char *name) > { > - unsigned int i = hash_name(name); > + unsigned int i; > + if (!m) > + return -1; > + > + i = hash_name(name); > struct labelmap_bucket *list = m->map_name[i]; I moved this a bit to avoid mixing declaration and code, but otherwise it should be the same change. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/src/conntrack/labels.c b/src/conntrack/labels.c index 8048076..6d811ad 100644 --- a/src/conntrack/labels.c +++ b/src/conntrack/labels.c @@ -51,7 +51,11 @@ static unsigned int hash_name(const char *name) int __labelmap_get_bit(struct nfct_labelmap *m, const char *name) { - unsigned int i = hash_name(name); + unsigned int i; + if (!m) + return -1; + + i = hash_name(name); struct labelmap_bucket *list = m->map_name[i]; while (list) {
When CONNLABEL_CFG isn't available (/etc/xtables/connlabel.conf), conntrack tool crashes: [marcos@Icarus ~]$ conntrack -l something nfct_labelmap_new: No such file or directory Segmentation fault (core dumped) I can see this problem in Fedora 26, because connlabel.conf does not come along the conntrack/libnetfilter packages. This problem happens because conntrack calls nfct_labelmap_new, which resides on libnetfilter_conntrack. So this lib returns NULL because CONNLABEL_CFG is not present, and then NULL is assigned to the global var called labelmap on conntrack. Later, get_label is called, passing NULL to the library, and __label_get_bit is called and deferences labelmap without check, which leads to a crash. With this patch on libnetlfilter_conntrack, the crash does not happen anymore, and an error message is displayed: [marcos@Icarus conntrack-tools]$ LD_LIBRARY_PATH=/mnt/data/gitroot/libnetfilter_conntrack/src/.libs/ conntrack -l something nfct_labelmap_new: No such file or directory conntrack v1.4.4 (conntrack-tools): unknown label 'something' Try `conntrack -h' or 'conntrack --help' for more information. Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com> --- This is my first patch to netfilter and conntrack-tools, so please let me know if I sent to the right place, or if the patch needs more work. That "No Such file..." comes from a perror on conntrack, when labelmap_init returns NULL. Thanks! src/conntrack/labels.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)