Description
In the Linux kernel, the following vulnerability has been resolved: s390/qeth: validate user buffer length in SNMP and ARP query ioctls qeth_snmp_command() and qeth_l3_arp_query() allocate a buffer sized by a user-supplied length (udata_len) without checking a lower bound, then set udata_offset to a fixed non-zero value and pass both to a reply callback. The callback bounds-checks the copy with if ((udata_len - udata_offset) < len) Both fields are u32, so a udata_len smaller than udata_offset makes the subtraction wrap and the check pass, and the following memcpy() writes past the allocation. A udata_len of 0 also yields ZERO_SIZE_PTR from kzalloc(), which the existing NULL check does not catch. Reject buffers smaller than udata_offset before allocating, so the callback subtraction can no longer underflow.
References8
- git.kernel.org/stable/c/3083818e67bcd656965797fbac9a3d6c1d44f78a
- git.kernel.org/stable/c/46443eaddebd84c51940857b11787229be169dec
- git.kernel.org/stable/c/75fb3151513d7d9f77a8f9545418279b119c06b8
- git.kernel.org/stable/c/91935843f9396a9e45253e2c0d4337ca1371754b
- git.kernel.org/stable/c/9d00eeb2d27f4cc817c5e408760226d43f811ec6
- git.kernel.org/stable/c/a3083647747942ea32faf14560d6397ff3068046
- git.kernel.org/stable/c/cc423f4105fe145b33e1d7cad34245a798358f73
- git.kernel.org/stable/c/d141f087b1af656f055d7c5793a3e87817ba0bbe
Metrics
- CVSS 3.1
-
8.4
HIGH
Score source: CNA
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 3 · as of 9 November 2026
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.