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 401011E47AD; Tue, 12 Aug 2025 19:28:53 +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=1755026933; cv=none; b=EHSWdYluEQWuTmqU9WhskFo1BDDwTvQjObR6+wfVor2EyGeu2gY8kXtZlVOBo9wpeOCi4rN2spzCMUDVLRk0Kus3Nae13OHwiUgn+x2CtSRYww/9s8mr2oDFNIfFW5HQsG2Ep3J87qFOt/fst65/BZjGjKBR0QyNeBXdTzEfaIA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755026933; c=relaxed/simple; bh=gDNpWiTBd0qE4tBWCUNdTqAJqGtM7Tf07Arok6bDBjI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uDM81BtlHZNK/wvW+RBm62/2doCk/BzvvV9xk33iS/sCYq9UVZrWolMqGrLkpbvCSpY6LxnVMgX+x9lsMkZAceoaIDhGN6Dnlcwi2bpAMQVO4VO9yZxYbv/op/63ABP5st9/DT9A8H3A7tKg1zb6noM10LTkmgeD48h2OV5g8GQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LOiOilDf; 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="LOiOilDf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BBAF0C4CEF0; Tue, 12 Aug 2025 19:28:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755026933; bh=gDNpWiTBd0qE4tBWCUNdTqAJqGtM7Tf07Arok6bDBjI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LOiOilDfaddiK90fbD3q/lkqVbAoASfU4mrHkUhQsSJV6FhpQ55IPOCHiEcxy3vFL tMzu7c69UyOz9SoiNdBNC3y2dAkRi4MTiCV0B67G5XZBaVgsPK93pBXtMu40kkmQ7m wcY9WR1SyqWkGqDg5KbJS6cTld3W+C9qyqDDlNqs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alan Stern , syzbot+b63d677d63bcac06cf90@syzkaller.appspotmail.com, Benjamin Tissoires Subject: [PATCH 6.15 477/480] HID: core: Harden s32ton() against conversion to 0 bits Date: Tue, 12 Aug 2025 19:51:25 +0200 Message-ID: <20250812174417.043753867@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250812174357.281828096@linuxfoundation.org> References: <20250812174357.281828096@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern commit a6b87bfc2ab5bccb7ad953693c85d9062aef3fdd upstream. Testing by the syzbot fuzzer showed that the HID core gets a shift-out-of-bounds exception when it tries to convert a 32-bit quantity to a 0-bit quantity. Ideally this should never occur, but there are buggy devices and some might have a report field with size set to zero; we shouldn't reject the report or the device just because of that. Instead, harden the s32ton() routine so that it returns a reasonable result instead of crashing when it is called with the number of bits set to 0 -- the same as what snto32() does. Signed-off-by: Alan Stern Reported-by: syzbot+b63d677d63bcac06cf90@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-usb/68753a08.050a0220.33d347.0008.GAE@google.com/ Tested-by: syzbot+b63d677d63bcac06cf90@syzkaller.appspotmail.com Fixes: dde5845a529f ("[PATCH] Generic HID layer - code split") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/613a66cd-4309-4bce-a4f7-2905f9bce0c9@rowland.harvard.edu Signed-off-by: Benjamin Tissoires Signed-off-by: Greg Kroah-Hartman --- drivers/hid/hid-core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -66,8 +66,12 @@ static s32 snto32(__u32 value, unsigned static u32 s32ton(__s32 value, unsigned int n) { - s32 a = value >> (n - 1); + s32 a; + if (!value || !n) + return 0; + + a = value >> (n - 1); if (a && a != -1) return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1; return value & ((1 << n) - 1);