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Date: Sun, 29 Mar 2015 16:05:28 +0200 From: Jiri Benc <jbenc@...hat.com> To: netdev@...r.kernel.org Cc: Thomas Graf <tgraf@...g.ch> Subject: [PATCH net] netlink: pad nla_memcpy dest buffer with zeroes This is especially important in cases where the kernel allocs a new structure and expects a field to be set from a netlink attribute. If such attribute is shorter than expected, the rest of the field is left containing previous data. When such field is read back by the user space, kernel memory content is leaked. Signed-off-by: Jiri Benc <jbenc@...hat.com> --- Alternatively, we may audit all callers of nla_memcpy; at least nf_nat_ipv6_nlattr_to_range, ip_vs_genl_parse_service, ieee802154_add_iface, ieee802154_llsec_parse_key and vxlan_nla_get_addr seem possible to suffer from this by a quick glance. However, the notion of "shorter attribute is understood as padded by zeroes" seems sensible to me. --- lib/nlattr.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/nlattr.c b/lib/nlattr.c index 76a1b59523ab..f5907d23272d 100644 --- a/lib/nlattr.c +++ b/lib/nlattr.c @@ -279,6 +279,8 @@ int nla_memcpy(void *dest, const struct nlattr *src, int count) int minlen = min_t(int, count, nla_len(src)); memcpy(dest, nla_data(src), minlen); + if (count > minlen) + memset(dest + minlen, 0, count - minlen); return minlen; } -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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