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authorDae R. Jeong <dae.r.jeong@kaist.ac.kr>2020-10-22 04:21:28 +0300
committerSong Liu <songliubraving@fb.com>2020-11-30 21:12:18 +0300
commitc731b84b51bf7fe83448bea8f56a6d55006b0615 (patch)
treeddbc3cb838bbfa8d271ff4904c89e2d7c3bcbe04 /drivers
parent4d063e646b4bfe8e74c0b4b78bf11c3a7b5d962a (diff)
downloadlinux-c731b84b51bf7fe83448bea8f56a6d55006b0615.tar.xz
md: fix a warning caused by a race between concurrent md_ioctl()s
Syzkaller reports a warning as belows. WARNING: CPU: 0 PID: 9647 at drivers/md/md.c:7169 ... Call Trace: ... RIP: 0010:md_ioctl+0x4017/0x5980 drivers/md/md.c:7169 RSP: 0018:ffff888096027950 EFLAGS: 00010293 RAX: ffff88809322c380 RBX: 0000000000000932 RCX: ffffffff84e266f2 RDX: 0000000000000000 RSI: ffffffff84e299f7 RDI: 0000000000000007 RBP: ffff888096027bc0 R08: ffff88809322c380 R09: ffffed101341a482 R10: ffff888096027940 R11: ffff88809a0d240f R12: 0000000000000932 R13: ffff8880a2c14100 R14: ffff88809a0d2268 R15: ffff88809a0d2408 __blkdev_driver_ioctl block/ioctl.c:304 [inline] blkdev_ioctl+0xece/0x1c10 block/ioctl.c:606 block_ioctl+0xee/0x130 fs/block_dev.c:1930 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe This is caused by a race between two concurrenct md_ioctl()s closing the array. CPU1 (md_ioctl()) CPU2 (md_ioctl()) ------ ------ set_bit(MD_CLOSING, &mddev->flags); did_set_md_closing = true; WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags)); if(did_set_md_closing) clear_bit(MD_CLOSING, &mddev->flags); Fix the warning by returning immediately if the MD_CLOSING bit is set in &mddev->flags which indicates that the array is being closed. Fixes: 065e519e71b2 ("md: MD_CLOSING needs to be cleared after called md_set_readonly or do_md_stop") Reported-by: syzbot+1e46a0864c1a6e9bd3d8@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Dae R. Jeong <dae.r.jeong@kaist.ac.kr> Signed-off-by: Song Liu <songliubraving@fb.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/md/md.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 3c79243e9d07..16a97dc385b4 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7589,8 +7589,11 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
err = -EBUSY;
goto out;
}
- WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags));
- set_bit(MD_CLOSING, &mddev->flags);
+ if (test_and_set_bit(MD_CLOSING, &mddev->flags)) {
+ mutex_unlock(&mddev->open_mutex);
+ err = -EBUSY;
+ goto out;
+ }
did_set_md_closing = true;
mutex_unlock(&mddev->open_mutex);
sync_blockdev(bdev);