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 9D74D19A29E; Sun, 23 Jun 2024 13:45:29 +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=1719150329; cv=none; b=QauLDRZpFym7deyXKd4cIgSIh3j93MYl8KGT/IzJr2CtFfHUkGCVyV37O6H7V/NMlz4h6pc7sPn0UrKsCeXSOZAcGV53P7BGm96pBkvq/NgNdCmQcz11ezhFokSazCoPQyaP0zKnStiEnTVSbg2XQZXdNeqo63z3nB3kGFwxQaA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719150329; c=relaxed/simple; bh=xRYwX0A8P+3xrPF560IY5kbgx5sO63zGx3/Hh1VbJuU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=p6kQI3uuRB3xh6a8rxenEZmssNk8U64OBgmB9KxlWysSruin96WMMQTw5dQSIka05IzdIvyjGX0WoP1WSDCpmAA5/QoEI7RHZK1OO3iktA8Kk9fh84yrzE+WLAgwp8czogsbkludeYevKUO+9mA2Y+q52NQ18QyXTYC8YUzlbWM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aqra/tYZ; 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="aqra/tYZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 943E8C2BD10; Sun, 23 Jun 2024 13:45:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719150329; bh=xRYwX0A8P+3xrPF560IY5kbgx5sO63zGx3/Hh1VbJuU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aqra/tYZ5teRp02YS1soCF+3LGMatTYZPmu1wr0fL+8hEpDlkACW+AXcYpYmM9ntW t4KiqCvOSdDOgJ2Ss1801rHjldX/DgeIf6FVLbOn8mowSAAZMKAyz4AB+hRJQ8KWXD 0MBue8iyRncOdDGPtktLDL5yw/agR3gg0J0KpZNXEGfiHfbRFDnWT3AoP7yv+zhbm0 X19i3udo7U2RTh+r4VofYhySOZPhSDiKHblyFtGLtqcGA8hiRr21ATZenzSSl9mhJD ri3OmDwpud0nOzITkK+Ks8R9DhQ9vJMH36/eAliCVUnkc4NwRM/0z7b9SGhsnsI546 idXbKWwkaY5RA== 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 6.1 07/12] fs/file: fix the check in find_next_fd() Date: Sun, 23 Jun 2024 09:45:10 -0400 Message-ID: <20240623134518.809802-7-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240623134518.809802-1-sashal@kernel.org> References: <20240623134518.809802-1-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 6.1.95 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 dbca26ef7a01a..69386c2e37c50 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