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 A2D8719DF47; Sun, 23 Jun 2024 13:45:50 +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=1719150350; cv=none; b=BiZblf6e7DCZ3z0XgHZl5XFFf5vdrf025JEmNOLyzV16MJrRxPujXKKfheby4sLcBY7aWJMfQyKMfs3DhwsbWqhm4ns7eNyNxtdKMhAQlvZrZ/Jx8mBv5wadiRIAzaxdHHADiU+fHWsgbI44kr35AckL8+At5evxs6k/6liyylI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719150350; c=relaxed/simple; bh=1arlDtgHpguiccwBbCbrhGnXQBqQ3up1z1HOu96MpWE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=fy2Sj/rD1rylOb+WvFSzLtouhKC15EgpsGlM8MqFXwXUueW1SVwejRsDq2V11MOiTDTNbNnI9restyeTzuXwNQ/vIv6YjLZtiKLk/YgRdYfzrwpPWBsGBmzhDesRD2j72gZJt1sB3nQ4NYDmtNO96pd+rLIXfInJrKTCS5POwfA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ePeu8DFz; 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="ePeu8DFz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9EE14C32781; Sun, 23 Jun 2024 13:45:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719150350; bh=1arlDtgHpguiccwBbCbrhGnXQBqQ3up1z1HOu96MpWE=; h=From:To:Cc:Subject:Date:From; b=ePeu8DFzS2ck/0P5aHOOZQWHUPukG1HoRy47N88LleS6tvLlPtnDezEdS+KA0lLVX WUlDH+XLB++BxiRw7B0e6lDCsFQhk7aKx+pC0lHFq2y+SpKMl9H9JECphDRSAELMN8 irBHiEATW47jfMMVQmUGrV49uzNMAjA5D2j63Y/T3a6vnOXdcMrzDCVBpqokU6jFif soK3mC3tDp4iNm0IJc50IJavi+k0lnYV/hJVzE2EKm41oi9gulUqPwzEco5TTzG2LF Y0Zpy/Sv7KmiqQlcJLtT957mLvSQKIgx8WJd855ayBvM1atssSDndQmWjtNmJHQoj4 y49mAM9KlwIhg== 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 5.4 1/2] fs/file: fix the check in find_next_fd() Date: Sun, 23 Jun 2024 09:45:46 -0400 Message-ID: <20240623134548.810179-1-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.278 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 e56059fa1b309..64892b7444191 100644 --- a/fs/file.c +++ b/fs/file.c @@ -462,12 +462,12 @@ 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