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ipv4: Check attribute length for RTA_GATEWAY in multipath route 

commit 7a3429bace0e08d94c39245631ea6bc109dafa49 upstream.

syzbot reported uninit-value:
============================================================
  BUG: KMSAN: uninit-value in fib_get_nhs+0xac4/0x1f80
  net/ipv4/fib_semantics.c:708
   fib_get_nhs+0xac4/0x1f80 net/ipv4/fib_semantics.c:708
   fib_create_info+0x2411/0x4870 net/ipv4/fib_semantics.c:1453
   fib_table_insert+0x45c/0x3a10 net/ipv4/fib_trie.c:1224
   inet_rtm_newroute+0x289/0x420 net/ipv4/fib_frontend.c:886

Add helper to validate RTA_GATEWAY length before using the attribute.

Fixes: 4e902c5741 ("[IPv4]: FIB configuration using struct fib_config")
Reported-by: syzbot+d4b9a2851cc3ce998741@syzkaller.appspotmail.com
Signed-off-by: David Ahern <dsahern@kernel.org>
Cc: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Ahern 2021-12-30 17:36:31 -07:00 committed by Greg Kroah-Hartman
parent 1f46721836
commit 125d91f072
1 changed files with 26 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
net/ipv4/fib_semantics.c
View File

@ -654,6 +654,19 @@ static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
return nhs;
}
static int fib_gw_from_attr(__be32 *gw, struct nlattr *nla,
struct netlink_ext_ack *extack)
{
if (nla_len(nla) < sizeof(*gw)) {
NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
return -EINVAL;
}
*gw = nla_get_in_addr(nla);
return 0;
}
/* only called when fib_nh is integrated into fib_info */
static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
int remaining, struct fib_config *cfg,
@ -696,7 +709,11 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
return -EINVAL;
}
if (nla) {
fib_cfg.fc_gw4 = nla_get_in_addr(nla);
ret = fib_gw_from_attr(&fib_cfg.fc_gw4, nla,
extack);
if (ret)
goto errout;
if (fib_cfg.fc_gw4)
fib_cfg.fc_gw_family = AF_INET;
} else if (nlav) {
@ -894,6 +911,7 @@ int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
attrlen = rtnh_attrlen(rtnh);
if (attrlen > 0) {
struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
int err;
nla = nla_find(attrs, attrlen, RTA_GATEWAY);
nlav = nla_find(attrs, attrlen, RTA_VIA);
@ -904,12 +922,17 @@ int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
}
if (nla) {
__be32 gw;
err = fib_gw_from_attr(&gw, nla, extack);
if (err)
return err;
if (nh->fib_nh_gw_family != AF_INET ||
nla_get_in_addr(nla) != nh->fib_nh_gw4)
gw != nh->fib_nh_gw4)
return 1;
} else if (nlav) {
struct fib_config cfg2;
int err;
err = fib_gw_from_via(&cfg2, nlav, extack);
if (err)