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drbd: fix regression: potential NULL pointer dereference 

recent commit
    drbd: always write bitmap on detach
introduced a bitmap writeout during detach,
which obviously needs some meta data device to write to.

Unfortunately, that same error path may be taken if we fail to attach,
e.g. due to UUID mismatch, after we changed state to D_ATTACHING,
but before the lower level device pointer is even assigned.

We need to test for presence of mdev->ldev.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Philipp Reisner 2012-10-19 14:19:23 +02:00
parent 4035e4c2eb
commit fd0017c124
2 changed files with 11 additions and 2 deletions
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5
drivers/block/drbd/drbd_int.h
View File

@ -2318,6 +2318,11 @@ static inline void drbd_md_flush(struct drbd_conf *mdev)
{ {
int r; int r;
if (mdev->ldev == NULL) {
dev_warn(DEV, "mdev->ldev == NULL in drbd_md_flush\n");
return;
}
if (test_bit(MD_NO_FUA, &mdev->flags)) if (test_bit(MD_NO_FUA, &mdev->flags))
return; return;

8
drivers/block/drbd/drbd_main.c
View File

@ -3235,8 +3235,12 @@ static int w_go_diskless(struct drbd_work *w, int unused)
* (Do we want a specific meta data flag for this?) * (Do we want a specific meta data flag for this?)
* *
* If that does not make it to stable storage either, * If that does not make it to stable storage either,
* we cannot do anything about that anymore. */ * we cannot do anything about that anymore.
if (mdev->bitmap) { *
* We still need to check if both bitmap and ldev are present, we may
* end up here after a failed attach, before ldev was even assigned.
*/
if (mdev->bitmap && mdev->ldev) {
if (drbd_bitmap_io_from_worker(mdev, drbd_bm_write, if (drbd_bitmap_io_from_worker(mdev, drbd_bm_write,
"detach", BM_LOCKED_MASK)) { "detach", BM_LOCKED_MASK)) {
if (test_bit(WAS_READ_ERROR, &mdev->flags)) { if (test_bit(WAS_READ_ERROR, &mdev->flags)) {