From: Paul Moore paul@paul-moore.com
[ Upstream commit 756125289285f6e55a03861bf4b6257aa3d19a93 ]
This patch ensures that we always check the netlink payload length in audit_receive_msg() before we take any action on the payload itself.
Cc: stable@vger.kernel.org Reported-by: syzbot+399c44bf1f43b8747403@syzkaller.appspotmail.com Reported-by: syzbot+e4b12d8d202701f08b6d@syzkaller.appspotmail.com Signed-off-by: Paul Moore paul@paul-moore.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/audit.c | 40 +++++++++++++++++++++------------------- 1 file changed, 21 insertions(+), 19 deletions(-)
diff --git a/kernel/audit.c b/kernel/audit.c index bdf0cf463815e..84c445db5fe1e 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -753,13 +753,11 @@ static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature audit_log_end(ab); }
-static int audit_set_feature(struct sk_buff *skb) +static int audit_set_feature(struct audit_features *uaf) { - struct audit_features *uaf; int i;
BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names)); - uaf = nlmsg_data(nlmsg_hdr(skb));
/* if there is ever a version 2 we should handle that here */
@@ -815,6 +813,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) { u32 seq; void *data; + int data_len; int err; struct audit_buffer *ab; u16 msg_type = nlh->nlmsg_type; @@ -838,6 +837,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) } seq = nlh->nlmsg_seq; data = nlmsg_data(nlh); + data_len = nlmsg_len(nlh);
switch (msg_type) { case AUDIT_GET: { @@ -859,7 +859,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) struct audit_status s; memset(&s, 0, sizeof(s)); /* guard against past and future API changes */ - memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh))); + memcpy(&s, data, min_t(size_t, sizeof(s), data_len)); if (s.mask & AUDIT_STATUS_ENABLED) { err = audit_set_enabled(s.enabled); if (err < 0) @@ -908,7 +908,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) return err; break; case AUDIT_SET_FEATURE: - err = audit_set_feature(skb); + if (data_len < sizeof(struct audit_features)) + return -EINVAL; + err = audit_set_feature(data); if (err) return err; break; @@ -920,6 +922,8 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
err = audit_filter_user(msg_type); if (err == 1) { /* match or error */ + char *str = data; + err = 0; if (msg_type == AUDIT_USER_TTY) { err = tty_audit_push_current(); @@ -928,19 +932,17 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) } mutex_unlock(&audit_cmd_mutex); audit_log_common_recv_msg(&ab, msg_type); - if (msg_type != AUDIT_USER_TTY) + if (msg_type != AUDIT_USER_TTY) { + /* ensure NULL termination */ + str[data_len - 1] = '\0'; audit_log_format(ab, " msg='%.*s'", AUDIT_MESSAGE_TEXT_MAX, - (char *)data); - else { - int size; - + str); + } else { audit_log_format(ab, " data="); - size = nlmsg_len(nlh); - if (size > 0 && - ((unsigned char *)data)[size - 1] == '\0') - size--; - audit_log_n_untrustedstring(ab, data, size); + if (data_len > 0 && str[data_len - 1] == '\0') + data_len--; + audit_log_n_untrustedstring(ab, str, data_len); } audit_set_portid(ab, NETLINK_CB(skb).portid); audit_log_end(ab); @@ -949,7 +951,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) break; case AUDIT_ADD_RULE: case AUDIT_DEL_RULE: - if (nlmsg_len(nlh) < sizeof(struct audit_rule_data)) + if (data_len < sizeof(struct audit_rule_data)) return -EINVAL; if (audit_enabled == AUDIT_LOCKED) { audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE); @@ -958,7 +960,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) return -EPERM; } err = audit_rule_change(msg_type, NETLINK_CB(skb).portid, - seq, data, nlmsg_len(nlh)); + seq, data, data_len); break; case AUDIT_LIST_RULES: err = audit_list_rules_send(skb, seq); @@ -972,7 +974,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) case AUDIT_MAKE_EQUIV: { void *bufp = data; u32 sizes[2]; - size_t msglen = nlmsg_len(nlh); + size_t msglen = data_len; char *old, *new;
err = -EINVAL; @@ -1049,7 +1051,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
memset(&s, 0, sizeof(s)); /* guard against past and future API changes */ - memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh))); + memcpy(&s, data, min_t(size_t, sizeof(s), data_len)); /* check if new data is valid */ if ((s.enabled != 0 && s.enabled != 1) || (s.log_passwd != 0 && s.log_passwd != 1))