From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 540F022A7F6; Sat, 12 Sep 2026 13:53:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789221188; cv=none; b=A2thYmiI4hlIgZhEe4dM76tfYrJCSlSino06cibzXrh5U33WMP4i7jdeoJxQRDn0Yp5U9StP72J7RCsYr1mUxbIndwIV1utlxlqX0H5KVG6XF+vwr3WDMyIOxL2/Gk0Qb7HJaYF5qFphgK+6zLWtv6Nd00+817iOTk5560PU9qM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789221188; c=relaxed/simple; bh=TyqbQPoiW41utsOhUlQJKghXSlytzbnXX8rJVb3J1v8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=U3fcmpqr3fG0IV/mvo9T+ZbpEKmafh40ePP6jHQvvZ5ji7STDHkY5H5bqdzd6zqSOnM4UsrmNgj1m7YGH/93LU+ZNmfAz3TYRrIX/aMVQxeTtnVdQGS3bzxiVedBHC2Q71oJxYJ3DPcOiI2PW3qfDE5Ll3bt3n6MNbkl+Kgq+QA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=j0RN7UAq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="j0RN7UAq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0C9161F000FF; Sat, 12 Sep 2026 13:53:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789221187; bh=SmQccNkd0bKNOpSs4eC82gu4c8LsmLvqGzRz80h3ODk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=j0RN7UAq5d8hULcqbQqB/cdeEryb3EuH6lE0PrGOntdM2SZUo0fwuVwhgyeqTtP6+ yu14cNNUYbXpcJvtlumS5PGWznxSMFbi0GVxV3X8WsJICqlhfhcR2o6F/2M7P5gYzk w5z4DlGhuDbUeb3hnDW1UfTia70iL3yBdX8zmbGk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+2280f1cca5e6b0c353e4@syzkaller.appspotmail.com, stable , Ivy Lopez , Takashi Iwai Subject: [PATCH 6.6 0331/1424] usb: gadget: f_midi2: fix use-after-free in string attribute show path Date: Sat, 12 Sep 2026 08:46:03 +0200 Message-ID: <20260912065614.700340339@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.279695368@linuxfoundation.org> References: <20260912065607.279695368@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ivy Lopez commit fed0aa7c6eaedc6c0d4e362fc91724aa47be4a7b upstream. f_midi2_opts_str_show() takes the string lock internally, but its callers dereference the opts->info. pointer before calling it, outside the lock. This races with f_midi2_opts_str_store(), which frees the old string under opts->lock when the attribute is written concurrently, the show path can read a pointer that gets freed before the lock inside str_show() is even taken. Change f_midi2_opts_str_show() to take a pointer to the string field, matching the existing pattern in f_midi2_opts_str_store(), and dereference it only after the lock is held. Update all three callers (iface_name, block name, and the EP string option macro) accordingly. Reported-by: syzbot+2280f1cca5e6b0c353e4@syzkaller.appspotmail.com Cc: stable Closes: https://syzkaller.appspot.com/bug?extid=2280f1cca5e6b0c353e4 Signed-off-by: Ivy Lopez Reviewed-by: Takashi Iwai Link: https://patch.msgid.link/20260816005434.34018-1-skunkolee@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_midi2.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/drivers/usb/gadget/function/f_midi2.c +++ b/drivers/usb/gadget/function/f_midi2.c @@ -2180,13 +2180,13 @@ end: /* generic show/store for string */ static ssize_t f_midi2_opts_str_show(struct f_midi2_opts *opts, - const char *str, char *page) + const char **strp, char *page) { int result = 0; mutex_lock(&opts->lock); - if (str) - result = scnprintf(page, PAGE_SIZE, "%s\n", str); + if (*strp) + result = scnprintf(page, PAGE_SIZE, "%s\n", *strp); mutex_unlock(&opts->lock); return result; } @@ -2280,7 +2280,7 @@ static ssize_t f_midi2_block_opts_name_s { struct f_midi2_block_opts *opts = to_f_midi2_block_opts(item); - return f_midi2_opts_str_show(opts->ep->opts, opts->info.name, page); + return f_midi2_opts_str_show(opts->ep->opts, &opts->info.name, page); } static ssize_t f_midi2_block_opts_name_store(struct config_item *item, @@ -2437,7 +2437,7 @@ static ssize_t f_midi2_ep_opts_##name##_ char *page) \ { \ struct f_midi2_ep_opts *opts = to_f_midi2_ep_opts(item); \ - return f_midi2_opts_str_show(opts->opts, opts->info.name, page);\ + return f_midi2_opts_str_show(opts->opts, &opts->info.name, page);\ } \ \ static ssize_t f_midi2_ep_opts_##name##_store(struct config_item *item, \ @@ -2592,7 +2592,7 @@ static ssize_t f_midi2_opts_iface_name_s { struct f_midi2_opts *opts = to_f_midi2_opts(item); - return f_midi2_opts_str_show(opts, opts->info.iface_name, page); + return f_midi2_opts_str_show(opts, &opts->info.iface_name, page); } static ssize_t f_midi2_opts_iface_name_store(struct config_item *item,