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 D6D641922C0; Sun, 23 Jun 2024 13:45:01 +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=1719150301; cv=none; b=YLtRcVlNdICCMRxBZTFqB12FSz/933OZ2hOAGtqfaf57ZPuPfzkN5eKpXYPVszBKKaQvOqdahV9IgnhvZl6ZzHiI+v81zKdk7oRHdgEOd8HVDQ6FRUdI2CHJSbDwnxdd94bxAs5VG6PbKfyJpb6S309Maj825NrjHn7PHtZ35Zs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719150301; c=relaxed/simple; bh=7FqicvDUYKPGZolfw+2sfBKMu8QQLpoAgoKBu9pkmws=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Z4GcfyCuB5tdvKLtVCUVpqC7V6KhZ7cTUHZLwc5Oy5hApOntELexmYSAbFS/YpKxwmqbHXcv7TxM2Csi9Bn2IGX+5CLzAs2IcvywTH8xP9wmgp0o/n9GS6ouYMdADS9SxVMmP0IBHPnxhyxi3jWq5DtQofneDIvYpjLyX2hVJ7M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=K4fwikI+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="K4fwikI+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C718FC2BD10; Sun, 23 Jun 2024 13:45:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719150301; bh=7FqicvDUYKPGZolfw+2sfBKMu8QQLpoAgoKBu9pkmws=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K4fwikI+vQ8IVZ9d2cngYy+NmQnTU9qFLPMfd3T7Kd8lY/++eANN2PEUVOlRhkp3V 9f+iQHPXxavKPNpyvbTcjUiHwzV7VBO5MnwZlSAlnQyuQslXVJF4q4GasEOhviyWOa zrZbdX8L9wHymwIgWKjbM/65o4PnsRfnwX3/8AAQ+0V14SvRCH2/Q0Su9px8Cut/XD Ee25nIeJCXdr+eZaF1a2B31fy/Wd4anqkzHfVOLzq/HnXw+e9Hcl2q0jPhx28+WkuP +8x1ERK2jv4mmWPIri6/xveFTEJlMCu+Tvo/hc5ggCc8HbMg8fksEaD0MK/a5baITk Mjvg22RZlwmeg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Yuntao Wang , Jan Kara , Christian Brauner , Sasha Levin , viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org Subject: [PATCH AUTOSEL 6.6 08/16] fs/file: fix the check in find_next_fd() Date: Sun, 23 Jun 2024 09:44:37 -0400 Message-ID: <20240623134448.809470-8-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240623134448.809470-1-sashal@kernel.org> References: <20240623134448.809470-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.35 Content-Transfer-Encoding: 8bit From: Yuntao Wang [ Upstream commit ed8c7fbdfe117abbef81f65428ba263118ef298a ] The maximum possible return value of find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit) is maxbit. This return value, multiplied by BITS_PER_LONG, gives the value of bitbit, which can never be greater than maxfd, it can only be equal to maxfd at most, so the following check 'if (bitbit > maxfd)' will never be true. Moreover, when bitbit equals maxfd, it indicates that there are no unused fds, and the function can directly return. Fix this check. Signed-off-by: Yuntao Wang Link: https://lore.kernel.org/r/20240529160656.209352-1-yuntao.wang@linux.dev Reviewed-by: Jan Kara Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/file.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/file.c b/fs/file.c index 3e4a4dfa38fca..a815f6eddc511 100644 --- a/fs/file.c +++ b/fs/file.c @@ -481,12 +481,12 @@ struct files_struct init_files = { static unsigned int find_next_fd(struct fdtable *fdt, unsigned int start) { - unsigned int maxfd = fdt->max_fds; + unsigned int maxfd = fdt->max_fds; /* always multiple of BITS_PER_LONG */ unsigned int maxbit = maxfd / BITS_PER_LONG; unsigned int bitbit = start / BITS_PER_LONG; bitbit = find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit) * BITS_PER_LONG; - if (bitbit > maxfd) + if (bitbit >= maxfd) return maxfd; if (bitbit > start) start = bitbit; -- 2.43.0