linux-kernel - [RFC 1/7] dlm: fix possible lkb

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Message-ID: <20240827180236.316946-2-aahringo@redhat.com>
Date: Tue, 27 Aug 2024 14:02:30 -0400
From: Alexander Aring <aahringo@...hat.com>
To: teigland@...hat.com
Cc: gfs2@...ts.linux.dev,
	song@...nel.org,
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Subject: [RFC 1/7] dlm: fix possible lkb_resource null dereference

This patch fixes a possible null pointer dereference when this function is
called from request_lock() as lkb->lkb_resource is not assigned yet,
only after validate_lock_args() by calling attach_lkb(). Another issue
is that a resource name could be a non printable bytearray and we cannot
assume to be ASCII coded.

In this patch we just drop the printout of the resource name, the lkb id
is enough to make a possible connection to a resource name if this
exists.

Signed-off-by: Alexander Aring <aahringo@...hat.com>
---
 fs/dlm/lock.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 0e8d2b9bf908..121d2976986b 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -2861,16 +2861,14 @@ static int validate_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
 	case -EINVAL:
 		/* annoy the user because dlm usage is wrong */
 		WARN_ON(1);
-		log_error(ls, "%s %d %x %x %x %d %d %s", __func__,
+		log_error(ls, "%s %d %x %x %x %d %d", __func__,
 			  rv, lkb->lkb_id, dlm_iflags_val(lkb), args->flags,
-			  lkb->lkb_status, lkb->lkb_wait_type,
-			  lkb->lkb_resource->res_name);
+			  lkb->lkb_status, lkb->lkb_wait_type);
 		break;
 	default:
-		log_debug(ls, "%s %d %x %x %x %d %d %s", __func__,
+		log_debug(ls, "%s %d %x %x %x %d %d", __func__,
 			  rv, lkb->lkb_id, dlm_iflags_val(lkb), args->flags,
-			  lkb->lkb_status, lkb->lkb_wait_type,
-			  lkb->lkb_resource->res_name);
+			  lkb->lkb_status, lkb->lkb_wait_type);
 		break;
 	}
 
-- 
2.43.0