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net/smc: check for missing nlattrs in SMC_PNETID messages 

It's possible to crash the kernel in several different ways by sending
messages to the SMC_PNETID generic netlink family that are missing the
expected attributes:

- Missing SMC_PNETID_NAME => null pointer dereference when comparing
  names.
- Missing SMC_PNETID_ETHNAME => null pointer dereference accessing
  smc_pnetentry::ndev.
- Missing SMC_PNETID_IBNAME => null pointer dereference accessing
  smc_pnetentry::smcibdev.
- Missing SMC_PNETID_IBPORT => out of bounds array access to
  smc_ib_device::pattr[-1].

Fix it by validating that all expected attributes are present and that
SMC_PNETID_IBPORT is nonzero.

Reported-by: syzbot+5cd61039dc9b8bfa6e47@syzkaller.appspotmail.com
Fixes: 6812baabf2 ("smc: establish pnet table management")
Cc: <stable@vger.kernel.org> # v4.11+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Biggers 2018-05-13 17:01:30 -07:00 committed by David S. Miller
parent 57f6f99fda
commit d49baa7e12
1 changed files with 40 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

71
net/smc/smc_pnet.c
View File

@ -245,40 +245,45 @@ static struct smc_ib_device *smc_pnet_find_ib(char *ib_name)
static int smc_pnet_fill_entry(struct net *net, struct smc_pnetentry *pnetelem,
struct nlattr *tb[])
{
char *string, *ibname = NULL;
int rc = 0;
char *string, *ibname;
int rc;
memset(pnetelem, 0, sizeof(*pnetelem));
INIT_LIST_HEAD(&pnetelem->list);
if (tb[SMC_PNETID_NAME]) {
string = (char *)nla_data(tb[SMC_PNETID_NAME]);
if (!smc_pnetid_valid(string, pnetelem->pnet_name)) {
rc = -EINVAL;
goto error;
}
}
if (tb[SMC_PNETID_ETHNAME]) {
string = (char *)nla_data(tb[SMC_PNETID_ETHNAME]);
pnetelem->ndev = dev_get_by_name(net, string);
if (!pnetelem->ndev)
return -ENOENT;
}
if (tb[SMC_PNETID_IBNAME]) {
ibname = (char *)nla_data(tb[SMC_PNETID_IBNAME]);
ibname = strim(ibname);
pnetelem->smcibdev = smc_pnet_find_ib(ibname);
if (!pnetelem->smcibdev) {
rc = -ENOENT;
goto error;
}
}
if (tb[SMC_PNETID_IBPORT]) {
pnetelem->ib_port = nla_get_u8(tb[SMC_PNETID_IBPORT]);
if (pnetelem->ib_port > SMC_MAX_PORTS) {
rc = -EINVAL;
goto error;
}
}
rc = -EINVAL;
if (!tb[SMC_PNETID_NAME])
goto error;
string = (char *)nla_data(tb[SMC_PNETID_NAME]);
if (!smc_pnetid_valid(string, pnetelem->pnet_name))
goto error;
rc = -EINVAL;
if (!tb[SMC_PNETID_ETHNAME])
goto error;
rc = -ENOENT;
string = (char *)nla_data(tb[SMC_PNETID_ETHNAME]);
pnetelem->ndev = dev_get_by_name(net, string);
if (!pnetelem->ndev)
goto error;
rc = -EINVAL;
if (!tb[SMC_PNETID_IBNAME])
goto error;
rc = -ENOENT;
ibname = (char *)nla_data(tb[SMC_PNETID_IBNAME]);
ibname = strim(ibname);
pnetelem->smcibdev = smc_pnet_find_ib(ibname);
if (!pnetelem->smcibdev)
goto error;
rc = -EINVAL;
if (!tb[SMC_PNETID_IBPORT])
goto error;
pnetelem->ib_port = nla_get_u8(tb[SMC_PNETID_IBPORT]);
if (pnetelem->ib_port < 1 || pnetelem->ib_port > SMC_MAX_PORTS)
goto error;
return 0;
error:
@ -307,6 +312,8 @@ static int smc_pnet_get(struct sk_buff *skb, struct genl_info *info)
void *hdr;
int rc;
if (!info->attrs[SMC_PNETID_NAME])
return -EINVAL;
pnetelem = smc_pnet_find_pnetid(
(char *)nla_data(info->attrs[SMC_PNETID_NAME]));
if (!pnetelem)
@ -359,6 +366,8 @@ static int smc_pnet_add(struct sk_buff *skb, struct genl_info *info)
static int smc_pnet_del(struct sk_buff *skb, struct genl_info *info)
{
if (!info->attrs[SMC_PNETID_NAME])
return -EINVAL;
return smc_pnet_remove_by_pnetid(
(char *)nla_data(info->attrs[SMC_PNETID_NAME]));
}