From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794341789; b=1eW4J9BumPBVVEGzb0ZjkC89d7HT88OKTrjQaGgNsIGbz//Xakf2HiMQLx1/EkFtbyqz MmWE00kLwKag3CV8DqzhKm+4o3j3Q2jbjSz65MbGSSz4tbpKC4V/11yp4IfRJ+oEH44DH jPWUmMZjM2Bu/BS816E+QaqLCGBNJtisq14cf3g37va482acvwwWn5XiO74+kj5jedRiP zLXtwhkGn6okXxgEf3c82V0882mbLR1SjB/BOkzdye20HeXLKgRQbMAoq0vU5j2JTBxr7 T5mQs8nqvp7O18gBQikrCxrcdcUKhsgMA2Sd3n6ocs2WAPe7NKCUnQ/6hqXWhd7NGgw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794341789; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=whqOxjUeWCaS2TujboeAUWI+1OnmZgKD0Mgj5wHfXuo=; b=AYkHgNSjcSfPsNIOwrdlQ3Vy9gJbsnKoxExXjIfXrbpDJifO2CKqHAinfvutA49UPlK2 ePLFeU/HHisb88ei2c8tfc/Wt8y6gOk6pjvMqhwjUtzYCRhyGUCDPWtgTDncnevOyf8DM yBQBk2j+Xsv5oxouzZrCWuosoUw9ziNkyfD1JwR7e6Vz8ywx4xUoSRAbm/zCvq/f7TF+J fRMjaecJaF/ytCugLAuOBtnQJL5i5GKR/0MHOVJKmmARAOoi/5GvkFed0FPoCk4QN7nh/ XLa6ENlpwg/lDG3ea8DH3P8XBk6soH3vyV45hh4gxbzIm7LLM1T7tpGMa39tKJv/Gbg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=QjdNvWpN; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 686B7606A323 for ; Tue, 10 Nov 2026 20:16:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=QjdNvWpN Received: by smtp.kernel.org (Postfix) with ESMTPSA id 82CFD1F008A4; Tue, 10 Nov 2026 20:16:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794341789; bh=whqOxjUeWCaS2TujboeAUWI+1OnmZgKD0Mgj5wHfXuo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QjdNvWpNTGgyLtEzLVIOAoiB6ArcCgEwmeYKqcgvO/qA3Vxi5uK5odZtP2f3h0jeM LwvZc/JDglJknEDlWu7p8eSZeFfGSGoq2Wd+zVQOGWtP6nycDCAuKPHT9MAhr7Jzdx qIP9Qngnc5NbyvivgRS0XjahWJAInpjO0rCUuQPkG5weuM0N8atHByLn7T+/wEV5iG RTy6dYtXzuLsD5KS5Xbi9s0wlOTE596picrq6SzdPc6UPR9Gvj+c+dtXsIhh4ZgQc0 /3c6Dq6pEVToRdwzalnYo4git6cmVrU20KstI0e1Bkk7mmNKsf1hKwpg7iktqW5sr1 tsidb1XypRTZA== From: Sasha Levin To: stable@vger.kernel.org Cc: Chi Zhiling , Namjae Jeon , Sasha Levin Subject: [PATCH 6.12.y] exfat: advance valid_size to EOF for append writes Date: Tue, 10 Nov 2026 15:16:27 -0500 Message-ID: <20261110201612.3747230-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107052509-failed-6.12-b70ab4075037@kernel.org> References: <20261107052509-failed-6.12-b70ab4075037@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chi Zhiling [ Upstream commit b70ab407503706289163dd59f1ac3e942bacc37d ] For an append write, the write position is recalculated by generic_write_checks(). Therefore, the write position must be obtained after generic_write_checks() returns. Using the original write position to advance valid_size may cause the valid_size update to be skipped, potentially exposing stale data. Also move the truncate_pagecache() check below the recalculated position, so that pos is never read before it is assigned. Fixes: 11a347fb6cef ("exfat: change to get file size from DataLength") Cc: stable@vger.kernel.org Signed-off-by: Chi Zhiling Signed-off-by: Namjae Jeon [ sashal: moved pos initialization before the existing direct I/O alignment checks ] Signed-off-by: Sasha Levin --- fs/exfat/file.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/fs/exfat/file.c b/fs/exfat/file.c index 033852efe5dc3..b624dc527f675 100644 --- a/fs/exfat/file.c +++ b/fs/exfat/file.c @@ -581,23 +581,18 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) struct file *file = iocb->ki_filp; struct inode *inode = file_inode(file); struct exfat_inode_info *ei = EXFAT_I(inode); - loff_t pos = iocb->ki_pos; - loff_t valid_size; + loff_t pos, valid_size; if (unlikely(exfat_forced_shutdown(inode->i_sb))) return -EIO; inode_lock(inode); - if (pos > i_size_read(inode)) - truncate_pagecache(inode, i_size_read(inode)); - - valid_size = ei->valid_size; - ret = generic_write_checks(iocb, iter); if (ret <= 0) goto unlock; + pos = iocb->ki_pos; if (iocb->ki_flags & IOCB_DIRECT) { unsigned long align = pos | iov_iter_alignment(iter); @@ -608,6 +603,10 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) } } + if (pos > i_size_read(inode)) + truncate_pagecache(inode, i_size_read(inode)); + + valid_size = ei->valid_size; if (pos > valid_size) { ret = exfat_extend_valid_size(file, pos); if (ret < 0 && ret != -ENOSPC) { @@ -617,6 +616,8 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) } if (ret < 0) goto unlock; + + pos = valid_size; } ret = __generic_file_write_iter(iocb, iter); @@ -625,9 +626,6 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) inode_unlock(inode); - if (pos > valid_size) - pos = valid_size; - if (iocb->ki_pos > pos) { ssize_t err = generic_write_sync(iocb, iocb->ki_pos - pos); if (err < 0) -- 2.53.0