From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Qiujun Huang <hqjagain@gmail.com>, Theodore Ts'o <tytso@mit.edu>,
Sasha Levin <sashal@kernel.org>,
linux-ext4@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 097/206] ext4: fix a data race at inode->i_disksize
Date: Thu, 17 Sep 2020 22:06:13 -0400 [thread overview]
Message-ID: <20200918020802.2065198-97-sashal@kernel.org> (raw)
In-Reply-To: <20200918020802.2065198-1-sashal@kernel.org>
From: Qiujun Huang <hqjagain@gmail.com>
[ Upstream commit dce8e237100f60c28cc66effb526ba65a01d8cb3 ]
KCSAN find inode->i_disksize could be accessed concurrently.
BUG: KCSAN: data-race in ext4_mark_iloc_dirty / ext4_write_end
write (marked) to 0xffff8b8932f40090 of 8 bytes by task 66792 on cpu 0:
ext4_write_end+0x53f/0x5b0
ext4_da_write_end+0x237/0x510
generic_perform_write+0x1c4/0x2a0
ext4_buffered_write_iter+0x13a/0x210
ext4_file_write_iter+0xe2/0x9b0
new_sync_write+0x29c/0x3a0
__vfs_write+0x92/0xa0
vfs_write+0xfc/0x2a0
ksys_write+0xe8/0x140
__x64_sys_write+0x4c/0x60
do_syscall_64+0x8a/0x2a0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
read to 0xffff8b8932f40090 of 8 bytes by task 14414 on cpu 1:
ext4_mark_iloc_dirty+0x716/0x1190
ext4_mark_inode_dirty+0xc9/0x360
ext4_convert_unwritten_extents+0x1bc/0x2a0
ext4_convert_unwritten_io_end_vec+0xc5/0x150
ext4_put_io_end+0x82/0x130
ext4_writepages+0xae7/0x16f0
do_writepages+0x64/0x120
__writeback_single_inode+0x7d/0x650
writeback_sb_inodes+0x3a4/0x860
__writeback_inodes_wb+0xc4/0x150
wb_writeback+0x43f/0x510
wb_workfn+0x3b2/0x8a0
process_one_work+0x39b/0x7e0
worker_thread+0x88/0x650
kthread+0x1d4/0x1f0
ret_from_fork+0x35/0x40
The plain read is outside of inode->i_data_sem critical section
which results in a data race. Fix it by adding READ_ONCE().
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Link: https://lore.kernel.org/r/1582556566-3909-1-git-send-email-hqjagain@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index cd833f4e64ef1..52be4c9650241 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5315,7 +5315,7 @@ static int ext4_do_update_inode(handle_t *handle,
raw_inode->i_file_acl_high =
cpu_to_le16(ei->i_file_acl >> 32);
raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
- if (ei->i_disksize != ext4_isize(inode->i_sb, raw_inode)) {
+ if (READ_ONCE(ei->i_disksize) != ext4_isize(inode->i_sb, raw_inode)) {
ext4_isize_set(raw_inode, ei->i_disksize);
need_datasync = 1;
}
--
2.25.1
next prev parent reply other threads:[~2020-09-18 2:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200918020802.2065198-1-sashal@kernel.org>
2020-09-18 2:05 ` [PATCH AUTOSEL 4.19 059/206] ext4: make dioread_nolock the default Sasha Levin
2020-09-18 2:58 ` Eric Biggers
2020-09-18 17:18 ` Theodore Y. Ts'o
2020-09-18 2:06 ` Sasha Levin [this message]
2020-09-18 2:06 ` [PATCH AUTOSEL 4.19 108/206] ext4: mark block bitmap corrupted when found instead of BUGON Sasha Levin
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