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 99D733769FF for ; Thu, 10 Sep 2026 02:11:08 +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=1789006269; cv=none; b=GicGpy0P9hFKxMJzKUMKpPNBBpJrq4cYfWIiJo4hLiI7Oq0xo3Y5N8q5qjlHc0HVBNyqCB5Mkw20L3svDYvxLXBzBp69leJaUVjWE/TKikIMCi2ubAt+Otb2XnarkXG/ATO7ugaGo8w68y0TNBneQ79Yb3Fl3K9NWLr0DUuIugU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789006269; c=relaxed/simple; bh=OniNcNS6EFqx4poXltPQeM0y9Ag321pgHnddYtcwuVM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=gwYdEIo/IsgOLPlaAYCqKxt58cpmeWFn3Zzr4exqowPzh7MnsefRFyW576sgD5be1EjeyR10ATcuGoNivZE0ht5EJx9NY60btDeQY721kZsMN1ysuV/Fd3KHLAi25N40GZaNxPhX9QYwK2RBlWVSlINQ3aFqnqAXruDbcS6AD0Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=USxCRb32; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="USxCRb32" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4406A1F000FF; Thu, 10 Sep 2026 02:11:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789006268; bh=KDbIlmzcBKYb/qo6/oi5i5bElV9FWeYhQm1sjuXd7MU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=USxCRb32CTM3FKx0IgvOXxEa+pODIMalGEdt2+H8LuFhKUwWFbCbED5QNugf9sMo7 rAZRjTRbnWW7ps6ntH5i2QarZfQzz11CQtnztZ94D+Ro+xt4Mn9aiEZ9rC5D30YZmE qcwX4v3BKBwSEqJ6GbVxXyw5uQsG1xMI5LUO0Sx8RPhQ+1kMeCBglioE1uyOVYKZLM b9X7Ktup9qCucTi3m8AGvY+SE/i7mfDapiInN6EEjtc49G8QCWPikFsokgm2Dp7ot1 jQ55/ZKY6xOQEr1/VCfmteQq1y6gxxrHBrHfMC8SPX7EhpcnU8xIVLp4Sn1Ma4i2iK CLkeW8lETq6GQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Jeffin Philip , syzbot+791be35f1fbcc85d06d7@syzkaller.appspotmail.com, stable , Alan Stern , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.12.y] usb: gadget: f_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers() Date: Wed, 9 Sep 2026 22:11:05 -0400 Message-ID: <20260910021105.3989086-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090850-exonerate-dumpster-494a@gregkh> References: <2026090850-exonerate-dumpster-494a@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jeffin Philip [ Upstream commit 2c0f5ca48674a5b5f9fa4a9c3325aa48053af0bc ] Previously fsg_num_buffers_validate() was removed as it was not necessary due to Kconfig setting the limits for n from 2 to 256 with default as 2. However, setting the page content in such a way that kstrtou8() reflects n value as either 0 or 1 bypasses these restrictions leading to a null pointer dereference if n is 0. Fix this by adding a check for n < 2 and returning -EINVAL if n is either 0 or 1 consistent with Kconfig logic. Reported-by: syzbot+791be35f1fbcc85d06d7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=791be35f1fbcc85d06d7 Fixes: fe5a6c48fd95 ("usb: gadget: storage: get rid of fsg_num_buffers_validate()") Cc: stable Signed-off-by: Jeffin Philip Acked-by: Alan Stern Link: https://patch.msgid.link/20260818035904.10324-1-jeffinphilip14@gmail.com Signed-off-by: Greg Kroah-Hartman [ adjusted context to retain the branch’s existing kcalloc() call instead of kzalloc_objs(). ] Signed-off-by: Sasha Levin --- drivers/usb/gadget/function/f_mass_storage.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c index 74cb7e57a197c..341cb3861a13f 100644 --- a/drivers/usb/gadget/function/f_mass_storage.c +++ b/drivers/usb/gadget/function/f_mass_storage.c @@ -2748,6 +2748,9 @@ int fsg_common_set_num_buffers(struct fsg_common *common, unsigned int n) struct fsg_buffhd *bh, *buffhds; int i; + if (n < 2) + return -EINVAL; + buffhds = kcalloc(n, sizeof(*buffhds), GFP_KERNEL); if (!buffhds) return -ENOMEM; -- 2.53.0