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 717903B530F; Thu, 15 Jan 2026 17:36:37 +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=1768498597; cv=none; b=qJowN/GLHMxuHndOCUChZmEF+ffX8fYazZsZyAvsq4lFqjRokpU8HhiF1VOeYdGcBp7UAsnQtmKE7eNKwKyZD/hLtuYQinbYxdINnWAT0UpLoSmsUrttQEgQvGmueXH0CxhhOHxHhySfzf82W1SPYx5r9v6VHTfUqDC1kzinQUg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768498597; c=relaxed/simple; bh=ASv9ZcMfgvHLHUxaxKE4/0FC7gH9z26tEJ4tLu4dT2E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Q+8KTCIWKb1KYV7Rw+GD9iq1WVN7BIVA5jSnGTd90H6+q3ToT6QYNn5UZl8sse/PEFolNlk8SV2e8s+2dWsHGP3R/B/oVw5AzhPCSfX/zZ37aT4EoStKEsn8ar++nybS6nCP+0Qha35eoNOgH/pVv9I0fxC8VaoGfXjs0TA58cw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KAqR+AR4; 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="KAqR+AR4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1910C116D0; Thu, 15 Jan 2026 17:36:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768498597; bh=ASv9ZcMfgvHLHUxaxKE4/0FC7gH9z26tEJ4tLu4dT2E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KAqR+AR4wD0tilK8yNPmMHeg8DO0gP/VhBP/cp1I0UMB4+zNq8YE7fJqFrH8S5Fr3 1/szZuHrzKsESE5Qhwm9r8BS1PQmmEEP7cj3PsOU/2dCVn7cecofz1T1Ul0lF2sW6E a6WpE6IDdmACd5zRnFwUAQhwEvoBcROnGRPg2Hes= 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 , Wenshan Lan Subject: [PATCH 5.15 486/554] HID: core: Harden s32ton() against conversion to 0 bits Date: Thu, 15 Jan 2026 17:49:12 +0100 Message-ID: <20260115164303.904225253@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164246.225995385@linuxfoundation.org> References: <20260115164246.225995385@linuxfoundation.org> User-Agent: quilt/0.69 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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern [ Upstream commit a6b87bfc2ab5bccb7ad953693c85d9062aef3fdd ] 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 [ s32ton() was moved by c653ffc28340 ("HID: stop exporting hid_snto32()"). Minor context change fixed. ] Signed-off-by: Wenshan Lan Signed-off-by: Greg Kroah-Hartman --- drivers/hid/hid-core.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1349,7 +1349,12 @@ EXPORT_SYMBOL_GPL(hid_snto32); static u32 s32ton(__s32 value, unsigned 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);