From 47984e9db9caaf76fc88c0080bd6402df58ff7ce Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Mon, 27 Apr 2026 07:30:37 -0700 Subject: [PATCH] netconsole: propagate device name truncation in dev_name_store() [ Upstream commit 92ceb7bff62c2606f664c204750eca0b85d44112 ] dev_name_store() calls strscpy(nt->np.dev_name, buf, IFNAMSIZ) without checking the return value. If userspace writes an interface name longer than IFNAMSIZ - 1, strscpy() silently truncates and returns -E2BIG, but the function ignores it and reports a fully successful write back to userspace. If a real interface happens to match the truncated name, netconsole will bind to the wrong device on the next enable, sending kernel logs and panic output to an unintended network segment with no indication to userspace that anything was rewritten. Reject writes whose length cannot fit in nt->np.dev_name up front: if (count >= IFNAMSIZ) return -ENAMETOOLONG; This is not a big deal of a problem, but, it is still the correct approach. Fixes: 0bcc1816188e57 ("[NET] netconsole: Support dynamic reconfiguration using configfs") Signed-off-by: Breno Leitao Link: https://patch.msgid.link/20260427-netconsole_ai_fixes-v2-3-59965f29d9cc@debian.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/netconsole.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index 7523f7763d36..06345487d6aa 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -694,6 +694,13 @@ static ssize_t dev_name_store(struct config_item *item, const char *buf, size_t count) { struct netconsole_target *nt = to_target(item); + size_t len = count; + + /* Account for a trailing newline appended by tools like echo */ + if (len && buf[len - 1] == '\n') + len--; + if (len >= IFNAMSIZ) + return -ENAMETOOLONG; mutex_lock(&dynamic_netconsole_mutex); if (nt->enabled) {