From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 77F711ADC83; Mon, 4 May 2026 14:09:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777903755; cv=none; b=NLcXqyRTbTWEkiWRf+MHXyVIQc13+5TNPX1zEH77UxJyVqa7B3Hm3gCQnMJz0jy7qcfm6/UxBnwVTysaeV65NYlLM6Mn+ACE9eyNAkGrMADHfsH3y23m3e9Jpd8palfqtnaqQCYXncBKYRHvC7JlIR4carLow40J5TYivXewvGE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777903755; c=relaxed/simple; bh=zZg0iAf4Xe56S6A0ttXnkZGnCyeRiqoJsJ1N0E+tqvc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RsTd8KR3s+iDLu4pN1s38Y7I/XWZu+ENdfrOjTJ0VSFMdBGxJoG4X51RLZqlaU1pNi1NmwU75fU6waKWzN88wSrC49wRGpKNE6bfNPxlJaBuNI8Wum9jrcn+2qjTZgEOGJWEoHxyszWk/+1m98Tz1KS9mzYRPuHhO5DhtQ2/IHk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FrBpOex+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FrBpOex+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FD89C2BCB8; Mon, 4 May 2026 14:09:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777903755; bh=zZg0iAf4Xe56S6A0ttXnkZGnCyeRiqoJsJ1N0E+tqvc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FrBpOex+YFTV60Stw1d2tV8UOsfYnH8PkAYbYou84Lb+7s0u2iioPKJzyWs/VB7ge s3EB6brTJtl5pTfx1+rPOcgnoCM0ZcpXqyr72lHRD1xmYmJV8G53mbHvnGpjFT4qaN I0pXBck5IpNK0NvICSCnle00BTrOtjN+FHbFxoYI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ziqing Chen , Takashi Iwai Subject: [PATCH 6.18 048/275] ALSA: control: Validate buf_len before strnlen() in snd_ctl_elem_init_enum_names() Date: Mon, 4 May 2026 15:49:48 +0200 Message-ID: <20260504135144.723152413@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260504135142.929052779@linuxfoundation.org> References: <20260504135142.929052779@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ziqing Chen commit e0da8a8cac74f4b9f577979d131f0d2b88a84487 upstream. snd_ctl_elem_init_enum_names() advances pointer p through the names buffer while decrementing buf_len. If buf_len reaches zero but items remain, the next iteration calls strnlen(p, 0). While strnlen(p, 0) returns 0 and would hit the existing name_len == 0 error path, CONFIG_FORTIFY_SOURCE's fortified strnlen() first checks maxlen against __builtin_dynamic_object_size(). When Clang loses track of p's object size inside the loop, this triggers a BRK exception panic before the return value is examined. Add a buf_len == 0 guard at the loop entry to prevent calling fortified strnlen() on an exhausted buffer. Found by kernel fuzz testing through Xiaomi Smartphone. Fixes: 8d448162bda5 ("ALSA: control: add support for ENUMERATED user space controls") Cc: stable@vger.kernel.org Signed-off-by: Ziqing Chen Link: https://patch.msgid.link/20260414132437.261304-1-chenziqing@xiaomi.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/control.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/sound/core/control.c +++ b/sound/core/control.c @@ -1574,6 +1574,10 @@ static int snd_ctl_elem_init_enum_names( /* check that there are enough valid names */ p = names; for (i = 0; i < ue->info.value.enumerated.items; ++i) { + if (buf_len == 0) { + kvfree(names); + return -EINVAL; + } name_len = strnlen(p, buf_len); if (name_len == 0 || name_len >= 64 || name_len == buf_len) { kvfree(names);