linux-stable.git/drivers/block/drbd, branch linux-5.10.y

drbd: fix "LOGIC BUG" in drbd_al_begin_io_nonblock()

2026-04-18T08:30:51+00:00

commit ab140365fb62c0bdab22b2f516aff563b2559e3b upstream.

Even though we check that we "should" be able to do lc_get_cumulative()
while holding the device->al_lock spinlock, it may still fail,
if some other code path decided to do lc_try_lock() with bad timing.

If that happened, we logged "LOGIC BUG for enr=...",
but still did not return an error.

The rest of the code now assumed that this request has references
for the relevant activity log extents.

The implcations are that during an active resync, mutual exclusivity of
resync versus application IO is not guaranteed. And a potential crash
at this point may not realizs that these extents could have been target
of in-flight IO and would need to be resynced just in case.

Also, once the request completes, it will give up activity log references it
does not even hold, which will trigger a BUG_ON(refcnt == 0) in lc_put().

Fix:

Do not crash the kernel for a condition that is harmless during normal
operation: also catch "e->refcnt == 0", not only "e == NULL"
when being noisy about "al_complete_io() called on inactive extent %u\n".

And do not try to be smart and "guess" whether something will work, then
be surprised when it does not.
Deal with the fact that it may or may not work.  If it does not, remember a
possible "partially in activity log" state (only possible for requests that
cross extent boundaries), and return an error code from
drbd_al_begin_io_nonblock().

A latter call for the same request will then resume from where we left off.

Cc: stable@vger.kernel.org
Signed-off-by: Lars Ellenberg 
Signed-off-by: Christoph Böhmwalder 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

drbd: add missing kref_get in handle_write_conflicts

2025-08-28T14:22:39+00:00

[ Upstream commit 00c9c9628b49e368d140cfa61d7df9b8922ec2a8 ]

With `two-primaries` enabled, DRBD tries to detect "concurrent" writes
and handle write conflicts, so that even if you write to the same sector
simultaneously on both nodes, they end up with the identical data once
the writes are completed.

In handling "superseeded" writes, we forgot a kref_get,
resulting in a premature drbd_destroy_device and use after free,
and further to kernel crashes with symptoms.

Relevance: No one should use DRBD as a random data generator, and apparently
all users of "two-primaries" handle concurrent writes correctly on layer up.
That is cluster file systems use some distributed lock manager,
and live migration in virtualization environments stops writes on one node
before starting writes on the other node.

Which means that other than for "test cases",
this code path is never taken in real life.

FYI, in DRBD 9, things are handled differently nowadays.  We still detect
"write conflicts", but no longer try to be smart about them.
We decided to disconnect hard instead: upper layers must not submit concurrent
writes. If they do, that's their fault.

Signed-off-by: Sarah Newman 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Christoph Böhmwalder 
Link: https://lore.kernel.org/r/20250627095728.800688-1-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

drbd: Add NULL check for net_conf to prevent dereference in state validation

2024-10-17T13:08:01+00:00

commit a5e61b50c9f44c5edb6e134ede6fee8806ffafa9 upstream.

If the net_conf pointer is NULL and the code attempts to access its
fields without a check, it will lead to a null pointer dereference.
Add a NULL check before dereferencing the pointer.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 44ed167da748 ("drbd: rcu_read_lock() and rcu_dereference() for tconn->net_conf")
Cc: stable@vger.kernel.org
Signed-off-by: Mikhail Lobanov 
Link: https://lore.kernel.org/r/20240909133740.84297-1-m.lobanov@rosalinux.ru
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

drbd: Fix atomicity violation in drbd_uuid_set_bm()

2024-10-17T13:08:01+00:00

commit 2f02b5af3a4482b216e6a466edecf6ba8450fa45 upstream.

The violation of atomicity occurs when the drbd_uuid_set_bm function is
executed simultaneously with modifying the value of
device->ldev->md.uuid[UI_BITMAP]. Consider a scenario where, while
device->ldev->md.uuid[UI_BITMAP] passes the validity check when its
value is not zero, the value of device->ldev->md.uuid[UI_BITMAP] is
written to zero. In this case, the check in drbd_uuid_set_bm might refer
to the old value of device->ldev->md.uuid[UI_BITMAP] (before locking),
which allows an invalid value to pass the validity check, resulting in
inconsistency.

To address this issue, it is recommended to include the data validity
check within the locked section of the function. This modification
ensures that the value of device->ldev->md.uuid[UI_BITMAP] does not
change during the validation process, thereby maintaining its integrity.

This possible bug is found by an experimental static analysis tool
developed by our team. This tool analyzes the locking APIs to extract
function pairs that can be concurrently executed, and then analyzes the
instructions in the paired functions to identify possible concurrency
bugs including data races and atomicity violations.

Fixes: 9f2247bb9b75 ("drbd: Protect accesses to the uuid set with a spinlock")
Cc: stable@vger.kernel.org
Signed-off-by: Qiu-ji Chen 
Reviewed-by: Philipp Reisner 
Link: https://lore.kernel.org/r/20240913083504.10549-1-chenqiuji666@gmail.com
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

drbd: correctly submit flush bio on barrier

2023-05-17T09:48:18+00:00

commit 3899d94e3831ee07ea6821c032dc297aec80586a upstream.

When we receive a flush command (or "barrier" in DRBD), we currently use
a REQ_OP_FLUSH with the REQ_PREFLUSH flag set.

The correct way to submit a flush bio is by using a REQ_OP_WRITE without
any data, and set the REQ_PREFLUSH flag.

Since commit b4a6bb3a67aa ("block: add a sanity check for non-write
flush/fua bios"), this triggers a warning in the block layer, but this
has been broken for quite some time before that.

So use the correct set of flags to actually make the flush happen.

Cc: Christoph Hellwig 
Cc: stable@vger.kernel.org
Fixes: f9ff0da56437 ("drbd: allow parallel flushes for multi-volume resources")
Reported-by: Thomas Voegtle 
Signed-off-by: Christoph Böhmwalder 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20230503121937.17232-1-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

drbd: fix an invalid memory access caused by incorrect use of list iterator

2023-01-14T09:15:32+00:00

[ Upstream commit ae4d37b5df749926891583d42a6801b5da11e3c1 ]

The bug is here:
	idr_remove(&connection->peer_devices, vnr);

If the previous for_each_connection() don't exit early (no goto hit
inside the loop), the iterator 'connection' after the loop will be a
bogus pointer to an invalid structure object containing the HEAD
(&resource->connections). As a result, the use of 'connection' above
will lead to a invalid memory access (including a possible invalid free
as idr_remove could call free_layer).

The original intention should have been to remove all peer_devices,
but the following lines have already done the work. So just remove
this line and the unneeded label, to fix this bug.

Cc: stable@vger.kernel.org
Fixes: c06ece6ba6f1b ("drbd: Turn connection->volumes into connection->peer_devices")
Signed-off-by: Xiaomeng Tong 
Reviewed-by: Christoph Böhmwalder 
Reviewed-by: Lars Ellenberg 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

drbd: use after free in drbd_create_device()

2022-11-25T16:45:47+00:00

[ Upstream commit a7a1598189228b5007369a9622ccdf587be0730f ]

The drbd_destroy_connection() frees the "connection" so use the _safe()
iterator to prevent a use after free.

Fixes: b6f85ef9538b ("drbd: Iterate over all connections")
Signed-off-by: Dan Carpenter 
Reviewed-by: Christoph Böhmwalder 
Link: https://lore.kernel.org/r/Y3Jd5iZRbNQ9w6gm@kili
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

drbd: fix duplicate array initializer

2022-06-09T08:21:01+00:00

[ Upstream commit 33cb0917bbe241dd17a2b87ead63514c1b7e5615 ]

There are two initializers for P_RETRY_WRITE:

drivers/block/drbd/drbd_main.c:3676:22: warning: initialized field overwritten [-Woverride-init]

Remove the first one since it was already ignored by the compiler
and reorder the list to match the enum definition. As P_ZEROES had
no entry, add that one instead.

Fixes: 036b17eaab93 ("drbd: Receiving part for the PROTOCOL_UPDATE packet")
Fixes: f31e583aa2c2 ("drbd: introduce P_ZEROES (REQ_OP_WRITE_ZEROES on the "wire")")
Signed-off-by: Arnd Bergmann 
Reviewed-by: Christoph Böhmwalder 
Link: https://lore.kernel.org/r/20220406190715.1938174-2-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

drbd: remove usage of list iterator variable after loop

2022-05-25T07:17:54+00:00

[ Upstream commit 901aeda62efa21f2eae937bccb71b49ae531be06 ]

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to iterate through the list [1].

Since that variable should not be used past the loop iteration, a
separate variable is used to 'remember the current location within the
loop'.

To either continue iterating from that position or skip the iteration
(if the previous iteration was complete) list_prepare_entry() is used.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel 
Link: https://lore.kernel.org/r/20220331220349.885126-1-jakobkoschel@gmail.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: drbd: drbd_nl: Make conversion to 'enum drbd_ret_code' explicit

2022-05-15T18:00:08+00:00

commit 1f1e87b4dc4598eac57a69868534b92d65e47e82 upstream.

Fixes the following W=1 kernel build warning(s):

 from drivers/block/drbd/drbd_nl.c:24:
 drivers/block/drbd/drbd_nl.c: In function ‘drbd_adm_set_role’:
 drivers/block/drbd/drbd_nl.c:793:11: warning: implicit conversion from ‘enum drbd_state_rv’ to ‘enum drbd_ret_code’ [-Wenum-conversion]
 drivers/block/drbd/drbd_nl.c:795:11: warning: implicit conversion from ‘enum drbd_state_rv’ to ‘enum drbd_ret_code’ [-Wenum-conversion]
 drivers/block/drbd/drbd_nl.c: In function ‘drbd_adm_attach’:
 drivers/block/drbd/drbd_nl.c:1965:10: warning: implicit conversion from ‘enum drbd_state_rv’ to ‘enum drbd_ret_code’ [-Wenum-conversion]
 drivers/block/drbd/drbd_nl.c: In function ‘drbd_adm_connect’:
 drivers/block/drbd/drbd_nl.c:2690:10: warning: implicit conversion from ‘enum drbd_state_rv’ to ‘enum drbd_ret_code’ [-Wenum-conversion]
 drivers/block/drbd/drbd_nl.c: In function ‘drbd_adm_disconnect’:
 drivers/block/drbd/drbd_nl.c:2803:11: warning: implicit conversion from ‘enum drbd_state_rv’ to ‘enum drbd_ret_code’ [-Wenum-conversion]

Cc: Philipp Reisner 
Cc: Lars Ellenberg 
Cc: Jens Axboe 
Cc: drbd-dev@lists.linbit.com
Cc: linux-block@vger.kernel.org
Signed-off-by: Lee Jones 
Link: https://lore.kernel.org/r/20210312105530.2219008-8-lee.jones@linaro.org
Signed-off-by: Jens Axboe 
Cc: Nathan Chancellor 
Signed-off-by: Greg Kroah-Hartman