From: Breno Leitao Date: Mon, 27 Apr 2026 14:30:37 +0000 (-0700) Subject: netconsole: propagate device name truncation in dev_name_store() X-Git-Tag: v7.1-rc2~22^2~13^2~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=92ceb7bff62c2606f664c204750eca0b85d44112;p=thirdparty%2Fkernel%2Flinux.git netconsole: propagate device name truncation in dev_name_store() 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 --- diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index 595e09bd1ccf..b3b36e3ddd03 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -817,6 +817,13 @@ 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; dynamic_netconsole_mutex_lock(); if (nt->state == STATE_ENABLED) {