libxtables: Avoid buffer overrun in xtables_compatible_revision()

The function is exported and accepts arbitrary strings as input. Calling
strcpy() without length checks is not OK.

Backport commit:
https://git.netfilter.org/iptables/commit/?id=f7d3dbb82e7ed94ccbf10cf70a3c7b3f3aaef1a1

Change-Id: Ibe4d0957fd6d9dd284ac3f84a328ea7b85e32b6b

diff --git a/libxtables/xtables.c b/libxtables/xtables.c
index d43f970..89a5f9c 100644 (file)
--- a/libxtables/xtables.c
+++ b/libxtables/xtables.c
@@ -799,7 +799,8 @@ int xtables_compatible_revision(const char *name, uint8_t revision, int opt)
 
        xtables_load_ko(xtables_modprobe_program, true);
 
-       strcpy(rev.name, name);
+       strncpy(rev.name, name, XT_EXTENSION_MAXNAMELEN - 1);
+       rev.name[XT_EXTENSION_MAXNAMELEN - 1] = '\0';
        rev.revision = revision;
 
        max_rev = getsockopt(sockfd, afinfo->ipproto, opt, &rev, &s);