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 A972955C329; Wed, 9 Sep 2026 14:14:50 +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=1788963291; cv=none; b=OegY1PER1KBGt1++y9Tt6YIV7OQHpQIyBalX/peP19ajGR93aNtTFgWmpXp//itsWI0LEtR8t9rzxzUWsV8cXmaFxExUgKG0KRFPzoykc97uReKHv6kV5x7fLmMLY/NB5GPJEoiZyzJbT5zkrwHFWS14A8ch5nQDvG3LxOH4dOM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788963291; c=relaxed/simple; bh=9sSKKg10RmKZfqG85QIvNKD/2/oHbyb7b9HnlH8LlL0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZTKDC2o0g4bb4/fCv2wqgCTAQveWcMd8aiVZtdhTvcFci3plq/zodQP7WRe1MORdNsk1W//lZRqyWg5WKsqIX39esCAVXtJ4TcHEU6MaNrQUPKa4HMgO8t6NKETNXHYqCeJVk0zygIICUr4w511IHH0NHm2x7ZNUhI22xlZD9AY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sGZqJCwg; 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="sGZqJCwg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 017AA1F00A3A; Wed, 9 Sep 2026 14:14:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788963290; bh=pttK7S9jHVBFUwp5uWq8QEXGhmV2LppbxqY0WTgz6kk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=sGZqJCwg1NljHyKXqeeNa/lKCBm+4ga1YJo+do+8uvOfXTnDXzC4WccvfV5Gu06Hc yDD25HklEH/AJSjOdvi7n1ib+0LUxayJZ8nSD/c5RFP1ebcolJD8GbPre7cn5cltvu 19Y8YBSS6P3aXWD7lQaRcCLAFun62a+QXpofsgkc= 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 6.18 028/583] usb: gadget: f_midi2: fix use-after-free in string attribute show path Date: Wed, 9 Sep 2026 15:35:13 +0200 Message-ID: <20260909134238.802615036@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260909134237.773280130@linuxfoundation.org> References: <20260909134237.773280130@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: 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 @@ -2178,13 +2178,13 @@ 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; } @@ -2278,7 +2278,7 @@ 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, @@ -2435,7 +2435,7 @@ 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, \ @@ -2590,7 +2590,7 @@ 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,