In the Linux kernel, the following vulnerability has been resolved:
neighbour: Enforce min/max to NDTPA_INTERVAL_PROBE_TIME_MS.
NDTPA_INTERVAL_PROBE_TIME_MS sets .type and .min but misses
.validation_type, so no validation is applied:
# ynl –family rt-neigh –do setneightbl
–json ‘{“name”: “arp_cache”, “parms”: {“interval-probe-time-ms”: 0}}’
# ynl –family rt-neigh –dump getneightbl –output-json |
jq ‘.[] | select(.name == “arp_cache” and has(“config”))
| .parms[“interval-probe-time-ms”]’
0
Moreover, nla_get_msecs() uses msecs_to_jiffies(), and u64 is
silently cast to u32, so a larger value can bypass the min check:
e.g. 4294967296 == 0x100000000
# ynl –family rt-neigh –do setneightbl
–json ‘{“name”: “arp_cache”, “parms”: {“interval-probe-time-ms”: 4294967296}}’
# ynl –family rt-neigh –dump getneightbl –output-json |
jq ‘.[] | select(.name == “arp_cache” and has(“config”))
| .parms[“interval-probe-time-ms”]’
0
msecs_to_jiffies() returns MAX_JIFFY_OFFSET if the value is
larger than INT_MAX. Also, INT_MAX ms overflows int NEIGH_VAR()
when HZ > 1000 (Alpha, MIPS), and passing a negative integer to
queue_delayed_work(unsigned long delay) causes sign extension,
which wraps around the expiry time to the past, resulting in it
being handled as 0 delay in the timer wheel.
Let’s use NLA_POLICY_FULL_RANGE() and limit the max to 1 day.
The same max check is applied to sysctl as well.
Note that this controls the probe interval for NTF_MANAGED
entries, so the max of 1 day is unlikely to break any
deployments.
