| Message ID | 20211211162148.74404-1-dsahern@kernel.org (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] ipv4: Check attribute length for RTA_GATEWAY | expand |
On Sat, Dec 11, 2021 at 09:21:48AM -0700, David Ahern wrote: > 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 length checking before using the attribute. > > Fixes: 4e902c57417c ("[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> > --- > I do not have KMSAN setup, so this is based on a code analysis. Before Was using this in the past: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs > 4e902c57417c fib_get_attr32 was checking the attribute length; the > switch to nla_get_u32 does not. > > net/ipv4/fib_semantics.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c > index 3cad543dc747..930843ba3b17 100644 > --- a/net/ipv4/fib_semantics.c > +++ b/net/ipv4/fib_semantics.c > @@ -704,6 +704,10 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh, > return -EINVAL; > } > if (nla) { > + if (nla_len(nla) < sizeof(__be32)) { > + NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY"); > + return -EINVAL; > + } Isn't the problem more general than that? It seems that there is no minimum length validation to any of the attributes inside RTA_MULTIPATH. Except maybe RTA_VIA > fib_cfg.fc_gw4 = nla_get_in_addr(nla); > if (fib_cfg.fc_gw4) > fib_cfg.fc_gw_family = AF_INET; > -- > 2.24.3 (Apple Git-128) >
On 12/11/21 12:13 PM, Ido Schimmel wrote: > On Sat, Dec 11, 2021 at 09:21:48AM -0700, David Ahern wrote: >> 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 length checking before using the attribute. >> >> Fixes: 4e902c57417c ("[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> >> --- >> I do not have KMSAN setup, so this is based on a code analysis. Before > > Was using this in the past: > https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs thanks for the pointer. I am a bit hardware challenged at the moment for out of tree features. > >> 4e902c57417c fib_get_attr32 was checking the attribute length; the >> switch to nla_get_u32 does not. >> >> net/ipv4/fib_semantics.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c >> index 3cad543dc747..930843ba3b17 100644 >> --- a/net/ipv4/fib_semantics.c >> +++ b/net/ipv4/fib_semantics.c >> @@ -704,6 +704,10 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh, >> return -EINVAL; >> } >> if (nla) { >> + if (nla_len(nla) < sizeof(__be32)) { >> + NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY"); >> + return -EINVAL; >> + } > > Isn't the problem more general than that? It seems that there is no > minimum length validation to any of the attributes inside RTA_MULTIPATH. > Except maybe RTA_VIA > A follow up commit is needed for RTA_FLOW.
On Sat, Dec 11, 2021 at 03:13:02PM -0700, David Ahern wrote: > On 12/11/21 12:13 PM, Ido Schimmel wrote: > > On Sat, Dec 11, 2021 at 09:21:48AM -0700, David Ahern wrote: > >> 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 length checking before using the attribute. > >> > >> Fixes: 4e902c57417c ("[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> > >> --- > >> I do not have KMSAN setup, so this is based on a code analysis. Before > > > > Was using this in the past: > > https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs > > thanks for the pointer. I am a bit hardware challenged at the moment for > out of tree features. > > > > >> 4e902c57417c fib_get_attr32 was checking the attribute length; the > >> switch to nla_get_u32 does not. > >> > >> net/ipv4/fib_semantics.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c > >> index 3cad543dc747..930843ba3b17 100644 > >> --- a/net/ipv4/fib_semantics.c > >> +++ b/net/ipv4/fib_semantics.c > >> @@ -704,6 +704,10 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh, > >> return -EINVAL; > >> } > >> if (nla) { > >> + if (nla_len(nla) < sizeof(__be32)) { > >> + NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY"); > >> + return -EINVAL; > >> + } > > > > Isn't the problem more general than that? It seems that there is no > > minimum length validation to any of the attributes inside RTA_MULTIPATH. > > Except maybe RTA_VIA > > > > A follow up commit is needed for RTA_FLOW. The same problem seems to exists in the delete path and IPv6. See fib_nh_match() and ip6_route_multipath_add(), for example.
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index 3cad543dc747..930843ba3b17 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -704,6 +704,10 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh, return -EINVAL; } if (nla) { + if (nla_len(nla) < sizeof(__be32)) { + NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY"); + return -EINVAL; + } fib_cfg.fc_gw4 = nla_get_in_addr(nla); if (fib_cfg.fc_gw4) fib_cfg.fc_gw_family = AF_INET;
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 length checking before using the attribute. Fixes: 4e902c57417c ("[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> --- I do not have KMSAN setup, so this is based on a code analysis. Before 4e902c57417c fib_get_attr32 was checking the attribute length; the switch to nla_get_u32 does not. net/ipv4/fib_semantics.c | 4 ++++ 1 file changed, 4 insertions(+)