From 7155e8e23455dd0256642ab76064087a1591ca22 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 17 Feb 2026 11:41:50 -0800 Subject: [PATCH] bpftool: Fix truncated netlink dumps Netlink requires that the recv buffer used during dumps is at least min(PAGE_SIZE, 8k) (see the man page). Otherwise the messages will get truncated. Make sure bpftool follows this requirement, avoid missing information on systems with large pages. Acked-by: Quentin Monnet Fixes: 7084566a236f ("tools/bpftool: Remove libbpf_internal.h usage in bpftool") Signed-off-by: Jakub Kicinski Link: https://lore.kernel.org/r/20260217194150.734701-1-kuba@kernel.org Signed-off-by: Alexei Starovoitov --- src/netlink.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/netlink.c b/src/netlink.c index c997e69..c9a78fb 100644 --- a/src/netlink.c +++ b/src/netlink.c @@ -143,7 +143,7 @@ static int libbpf_netlink_recv(int sock, __u32 nl_pid, int seq, struct nlmsghdr *nh; int len, ret; - ret = alloc_iov(&iov, 4096); + ret = alloc_iov(&iov, 8192); if (ret) goto done; @@ -212,6 +212,8 @@ start: } } } + if (len) + pr_warn("Invalid message or trailing data in Netlink response: %d bytes left\n", len); } ret = 0; done: