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

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

Posted by Mikhail Lobanov 2 months, 3 weeks ago

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 <m.lobanov@rosalinux.ru>
---
 drivers/block/drbd/drbd_state.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index 287a8d1d3f70..87cf5883078f 100644
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -876,7 +876,7 @@ is_valid_state(struct drbd_device *device, union drbd_state ns)
 		  ns.disk == D_OUTDATED)
 		rv = SS_CONNECTED_OUTDATES;
 
-	else if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
+	else if (nc && (ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
 		 (nc->verify_alg[0] == 0))
 		rv = SS_NO_VERIFY_ALG;
 
-- 
2.43.0

Re: [PATCH] drbd: Add NULL check for net_conf to prevent dereference in state validation

Posted by Jens Axboe 2 months, 3 weeks ago

On Mon, 09 Sep 2024 09:37:36 -0400, Mikhail Lobanov wrote:
> 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.
> 
> 
> [...]

Applied, thanks!

[1/1] drbd: Add NULL check for net_conf to prevent dereference in state validation
      commit: de068f4741781bbba0568b44b41d51da0feef6f9

Best regards,
-- 
Jens Axboe