From: Ido Schimmel idosch@nvidia.com
[ Upstream commit 9e17f99220d111ea031b44153fdfe364b0024ff2 ]
The 'TCA_MPLS_LABEL' attribute is of 'NLA_U32' type, but has a validation type of 'NLA_VALIDATE_FUNCTION'. This is an invalid combination according to the comment above 'struct nla_policy':
" Meaning of `validate' field, use via NLA_POLICY_VALIDATE_FN: NLA_BINARY Validation function called for the attribute. All other Unused - but note that it's a union "
This can trigger the warning [1] in nla_get_range_unsigned() when validation of the attribute fails. Despite being of 'NLA_U32' type, the associated 'min'/'max' fields in the policy are negative as they are aliased by the 'validate' field.
Fix by changing the attribute type to 'NLA_BINARY' which is consistent with the above comment and all other users of NLA_POLICY_VALIDATE_FN(). As a result, move the length validation to the validation function.
No regressions in MPLS tests:
# ./tdc.py -f tc-tests/actions/mpls.json [...] # echo $? 0
[1] WARNING: CPU: 0 PID: 17743 at lib/nlattr.c:118 nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117 Modules linked in: CPU: 0 PID: 17743 Comm: syz-executor.0 Not tainted 6.1.0-rc8 #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014 RIP: 0010:nla_get_range_unsigned+0x1d8/0x1e0 lib/nlattr.c:117 [...] Call Trace: <TASK> __netlink_policy_dump_write_attr+0x23d/0x990 net/netlink/policy.c:310 netlink_policy_dump_write_attr+0x22/0x30 net/netlink/policy.c:411 netlink_ack_tlv_fill net/netlink/af_netlink.c:2454 [inline] netlink_ack+0x546/0x760 net/netlink/af_netlink.c:2506 netlink_rcv_skb+0x1b7/0x240 net/netlink/af_netlink.c:2546 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:6109 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x5e9/0x6b0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x739/0x860 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0x38f/0x500 net/socket.c:2482 ___sys_sendmsg net/socket.c:2536 [inline] __sys_sendmsg+0x197/0x230 net/socket.c:2565 __do_sys_sendmsg net/socket.c:2574 [inline] __se_sys_sendmsg net/socket.c:2572 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2572 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
Link: https://lore.kernel.org/netdev/CAO4mrfdmjvRUNbDyP0R03_DrD_eFCLCguz6OxZ2TYRSv... Fixes: 2a2ea50870ba ("net: sched: add mpls manipulation actions to TC") Reported-by: Wei Chen harperchen1110@gmail.com Tested-by: Wei Chen harperchen1110@gmail.com Signed-off-by: Ido Schimmel idosch@nvidia.com Reviewed-by: Alexander Duyck alexanderduyck@fb.com Link: https://lore.kernel.org/r/20230107171004.608436-1-idosch@nvidia.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/sched/act_mpls.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c index 8ad25cc8ccd5..ea5959094adb 100644 --- a/net/sched/act_mpls.c +++ b/net/sched/act_mpls.c @@ -132,6 +132,11 @@ static int valid_label(const struct nlattr *attr, { const u32 *label = nla_data(attr);
+ if (nla_len(attr) != sizeof(*label)) { + NL_SET_ERR_MSG_MOD(extack, "Invalid MPLS label length"); + return -EINVAL; + } + if (*label & ~MPLS_LABEL_MASK || *label == MPLS_LABEL_IMPLNULL) { NL_SET_ERR_MSG_MOD(extack, "MPLS label out of range"); return -EINVAL; @@ -143,7 +148,8 @@ static int valid_label(const struct nlattr *attr, static const struct nla_policy mpls_policy[TCA_MPLS_MAX + 1] = { [TCA_MPLS_PARMS] = NLA_POLICY_EXACT_LEN(sizeof(struct tc_mpls)), [TCA_MPLS_PROTO] = { .type = NLA_U16 }, - [TCA_MPLS_LABEL] = NLA_POLICY_VALIDATE_FN(NLA_U32, valid_label), + [TCA_MPLS_LABEL] = NLA_POLICY_VALIDATE_FN(NLA_BINARY, + valid_label), [TCA_MPLS_TC] = NLA_POLICY_RANGE(NLA_U8, 0, 7), [TCA_MPLS_TTL] = NLA_POLICY_MIN(NLA_U8, 1), [TCA_MPLS_BOS] = NLA_POLICY_RANGE(NLA_U8, 0, 1),