Messages in this thread |  | | From | Hangbin Liu <> | | Subject | [PATCH net-next 0/4] ynl/ethtool/netlink: warn nla_len overflow for large string sets | | Date | Tue, 31 Mar 2026 11:56:10 +0800 |
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This series addresses a silent data corruption issue triggered when ynl retrieves string sets from NICs with a large number of statistics entries (e.g. mlx5_core with thousands of ETH_SS_STATS strings).
The root cause is that struct nlattr.nla_len is a __u16 (max 65535 bytes). When a NIC exports enough statistics strings, the ETHTOOL_A_STRINGSET_STRINGS nest built by strset_fill_set() exceeds this limit. nla_nest_end() silently truncates the length on assignment, producing a corrupted netlink message. In the doit path the corrupted message is delivered to userspace without any error; in the dumpit path an -EMSGSIZE may be returned if the data does not fit in the dump skb.
Patch 1 improves the userspace tool: rename the doit/dumpit helpers to do_set/do_get and convert do_get to use ynl.do() with an explicit device header instead of a full dump with client-side filtering.
Patch 2 adds a --dbg-small-recv option to the YNL ethtool tool, matching the same option already present in cli.py, to aid debugging of netlink message size issues.
Patch 3 is the kernel fix: check whether the strings_attr nest would exceed U16_MAX before calling nla_nest_end() in strset_fill_set(), and return -EMSGSIZE early if so.
Patch 4 adds a generic WARN_ON_ONCE() in nla_nest_end() itself, so that any future caller hitting the same overflow is immediately visible in the kernel log rather than silently corrupting data.
--- Hangbin Liu (4): tools: ynl: ethtool: use doit instead of dumpit for per-device GET tools: ynl: ethtool: add --dbg-small-recv option ethtool: strset: check nla_len overflow before nla_nest_end netlink: warn on nla_len overflow in nla_nest_end()
include/net/netlink.h | 1 + net/ethtool/strset.c | 4 +++ tools/net/ynl/pyynl/ethtool.py | 77 ++++++++++++++++++++++-------------------- 3 files changed, 46 insertions(+), 36 deletions(-) --- base-commit: dc9e9d61e301c087bcd990dbf2fa18ad3e2e1429 change-id: 20260324-b4-ynl_ethtool-f87cd42f572c
Best regards, -- Hangbin Liu <liuhangbin@gmail.com>
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