diff options
| author | Bodo Stroesser <bostroesser@gmail.com> | 2022-05-17 21:29:13 +0200 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2022-05-19 20:16:27 -0400 |
| commit | 325d5c5fb216674296f3902a8902b942da3adc5b (patch) | |
| tree | 98cee22612befcbff95316d83366e73fc4e6ecd2 /drivers/target | |
| parent | d627660c22b51121262c03dfa1a51bf54361f5a9 (diff) | |
scsi: target: tcmu: Avoid holding XArray lock when calling lock_page
In tcmu_blocks_release(), lock_page() is called to prevent a race causing
possible data corruption. Since lock_page() might sleep, calling it while
holding XArray lock is a bug.
To fix this, replace the xas_for_each() call with xa_for_each_range().
Since the latter does its own handling of XArray locking, the xas_lock()
and xas_unlock() calls around the original loop are no longer necessary.
The switch to xa_for_each_range() slows down the loop slightly. This is
acceptable since tcmu_blocks_release() is not relevant for performance.
Link: https://lore.kernel.org/r/20220517192913.21405-1-bostroesser@gmail.com
Fixes: bb9b9eb0ae2e ("scsi: target: tcmu: Fix possible data corruption")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/target')
| -rw-r--r-- | drivers/target/target_core_user.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c index b1fd06edea59..3deaeecb712e 100644 --- a/drivers/target/target_core_user.c +++ b/drivers/target/target_core_user.c @@ -1661,13 +1661,14 @@ static int tcmu_check_and_free_pending_cmd(struct tcmu_cmd *cmd) static u32 tcmu_blocks_release(struct tcmu_dev *udev, unsigned long first, unsigned long last) { - XA_STATE(xas, &udev->data_pages, first * udev->data_pages_per_blk); struct page *page; + unsigned long dpi; u32 pages_freed = 0; - xas_lock(&xas); - xas_for_each(&xas, page, (last + 1) * udev->data_pages_per_blk - 1) { - xas_store(&xas, NULL); + first = first * udev->data_pages_per_blk; + last = (last + 1) * udev->data_pages_per_blk - 1; + xa_for_each_range(&udev->data_pages, dpi, page, first, last) { + xa_erase(&udev->data_pages, dpi); /* * While reaching here there may be page faults occurring on * the to-be-released pages. A race condition may occur if @@ -1691,7 +1692,6 @@ static u32 tcmu_blocks_release(struct tcmu_dev *udev, unsigned long first, __free_page(page); pages_freed++; } - xas_unlock(&xas); atomic_sub(pages_freed, &global_page_count); |