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| author | Cen Zhang (Microsoft) <blbllhy@gmail.com> | 2026-07-14 00:15:41 -0400 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2026-07-23 11:41:03 +0200 |
| commit | 9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8 (patch) | |
| tree | 196065c5edf4c55fb28fd65a892f89c96849ac70 | |
| parent | f43ee0c0730d6191629b5ee1ceae27b1ebfdc047 (diff) | |
| download | linux-9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8.tar.gz linux-9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8.zip | |
tipc: fix u16 MTU truncation in media and bearer MTU validation
Both TIPC_NL_MEDIA_SET and TIPC_NL_BEARER_SET accept user-supplied
MTU values but only enforce a minimum bound, not a maximum. When a user
sets the MTU to a value exceeding U16_MAX (65535), it passes validation
but is silently truncated when assigned to u16 fields l->mtu and
l->advertised_mtu in tipc_link_create(). Values like 65536 (0x10000)
truncate to 0, causing a division by zero in tipc_link_set_queue_limits()
which computes TIPC_MAX_PUBL / (l->mtu / ITEM_SIZE). Other overflowing
values (e.g. 65537-131071) produce small incorrect MTU values, resulting
in link malfunction behaviors.
Crash stack (triggered as unprivileged user via user namespace):
tipc_link_set_queue_limits net/tipc/link.c:2531
tipc_link_create net/tipc/link.c:520
tipc_node_check_dest net/tipc/node.c:1279
tipc_disc_rcv net/tipc/discover.c:252
tipc_rcv net/tipc/node.c:2129
tipc_udp_recv net/tipc/udp_media.c:392
Two independent paths lack the upper bound check:
1. tipc_udp_mtu_bad() -- called from __tipc_nl_media_set() (MEDIA_SET)
2. inline check in __tipc_nl_bearer_set() at bearer.c:1160 (BEARER_SET)
Fix both by rejecting MTU values above U16_MAX.
Fixes: 901271e0403a ("tipc: implement configuration of UDP media MTU")
Reported-by: AutonomousCodeSecurity@microsoft.com
Closes: https://lore.kernel.org/all/CAB8m9WgETt0AjmFwE=F-CKjGXsK6_WDv0=kbYRcC8-noo+amnA@mail.gmail.com
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Cen Zhang (Microsoft) <blbllhy@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260714041541.307702-1-blbllhy@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
| -rw-r--r-- | net/tipc/netlink.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/net/tipc/netlink.c b/net/tipc/netlink.c index 8336a9664703..1307dd1a9613 100644 --- a/net/tipc/netlink.c +++ b/net/tipc/netlink.c @@ -113,12 +113,16 @@ const struct nla_policy tipc_nl_node_policy[TIPC_NLA_NODE_MAX + 1] = { }; /* Properties valid for media, bearer and link */ +static const struct netlink_range_validation tipc_nl_mtu_range = { + .max = U16_MAX, +}; + const struct nla_policy tipc_nl_prop_policy[TIPC_NLA_PROP_MAX + 1] = { [TIPC_NLA_PROP_UNSPEC] = { .type = NLA_UNSPEC }, [TIPC_NLA_PROP_PRIO] = { .type = NLA_U32 }, [TIPC_NLA_PROP_TOL] = { .type = NLA_U32 }, [TIPC_NLA_PROP_WIN] = { .type = NLA_U32 }, - [TIPC_NLA_PROP_MTU] = { .type = NLA_U32 }, + [TIPC_NLA_PROP_MTU] = NLA_POLICY_FULL_RANGE(NLA_U32, &tipc_nl_mtu_range), [TIPC_NLA_PROP_BROADCAST] = { .type = NLA_U32 }, [TIPC_NLA_PROP_BROADCAST_RATIO] = { .type = NLA_U32 } }; |