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ip maddr: fix filtering by device 

Commit 530903dd90 ("ip: fix igmp parsing when iface is long") uses
variable len to keep trailing colon from interface name comparison.  This
variable is local to loop body but we set it in one pass and use it in
following one(s) so that we are actually using (pseudo)random length for
comparison. This became apparent since commit b48a1161f5 ("ipmaddr: Avoid
accessing uninitialized data") always initializes len to zero so that the
name comparison is always true. As a result, "ip maddr show dev eth0" shows
IPv4 multicast addresses for all interfaces.

Instead of keeping the length, let's simply replace the trailing colon with
a null byte. The bonus is that we get correct interface name in ma.name.

Fixes: 530903dd90 ("ip: fix igmp parsing when iface is long")
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Phil Sutter <phil@nwl.cc>
Acked-by: Petr Vorel <pvorel@suse.cz>
This commit is contained in:
Michal Kubecek 2017-10-19 10:21:08 +02:00 committed by Stephen Hemminger
parent 572e893613
commit 21503ed2af
1 changed files with 4 additions and 3 deletions
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7
ip/ipmaddr.c
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@ -136,17 +136,18 @@ static void read_igmp(struct ma_info **result_p)
while (fgets(buf, sizeof(buf), fp)) {
struct ma_info *ma;
size_t len = 0;
if (buf[0] != '\t') {
size_t len;
sscanf(buf, "%d%s", &m.index, m.name);
len = strlen(m.name);
if (m.name[len - 1] == ':')
len--;
m.name[len - 1] = '\0';
continue;
}
if (filter.dev && strncmp(filter.dev, m.name, len))
if (filter.dev && strcmp(filter.dev, m.name))
continue;
sscanf(buf, "%08x%d", (__u32 *)&m.addr.data, &m.users);