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 D1AFC19DFB6; Sun, 23 Jun 2024 13:45:54 +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=1719150354; cv=none; b=nMg3PKvlzLojF34pUz+GinQ6CqeF3fei0FQzQK43JEnNCmkhd3YbSI8H+UrKNfHKaZ8crbyvaIqcmLGFljYzcaYsgJtr/MNRJenDQ+D+wfsh4YHZ+gGAL2sFGAd+d70s2NEwwjmP5vJAjygNBtK5jH4OZgcbtaPDbanczuNJQEk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719150354; c=relaxed/simple; bh=0DJhXcCP6xNT6lRJrJuYYfSYebrsuIwNcCS1nHAkHoE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=aX508BWuYd5ypqyyvg3g4CMYkQZxrKrQSGuS3ooeFqLY4PBxKHcVJeRWAsaO4Ml4OS1vf9R5PyiqTzl0Ec8yrSoscGzd/JGHM7ztkrd+ZIqSWfcEs8pwNSNZmVc2gaZEfqWhkIA4Tn7d6xles5Tdop9ilq19GfhQMqNOmICqFr4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fSTOo2P9; 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="fSTOo2P9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1B44C32781; Sun, 23 Jun 2024 13:45:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719150354; bh=0DJhXcCP6xNT6lRJrJuYYfSYebrsuIwNcCS1nHAkHoE=; h=From:To:Cc:Subject:Date:From; b=fSTOo2P9kB3ZplXCUZvv0ECR7gfwG0l/MD7Qz5BygHACwoK0kMvhlesfHRFQMxtao F4m1HIlyNIPOqhCr8/UciwfiESbuVraDFhReR5hozPD76o1E+2O8Qnb0TmLzoc6Xds eLVbM4X/xTW7GQv7F9KyTkIQ1ie522f/kciFrQVD9r5yRyChPzxN5elPlPSfCPFF7h pkR4dV+6VVvrQSe2/p47sno6L3ZBygywe8QhOJDgAFBq7fR4TNUsmHD4bHI0yw1uBs 83SETrhewxljLnoM7YdqhRXS0tcF3+wA85vBjQwPHpJQ4CTNimtKD6vcye+W+NX+Zw XzlNWsTxAfTcg== 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 4.19 1/2] fs/file: fix the check in find_next_fd() Date: Sun, 23 Jun 2024 09:45:51 -0400 Message-ID: <20240623134552.810231-1-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 4.19.316 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 928ba7b8df1e9..f5ba0e6f1a4c6 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