[Devel] [PATCH RHEL9 COMMIT] fs/fuse kio: convert BUG_ON check to error handling

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.0-427.44.1.vz9.80.x-ovz" and will appear at git at bitbucket.org:openvz/vzkernel.git
after rh9-5.14.0-427.44.1.vz9.80.22
------>
commit c7c6b9d910e80fdbfb43e1abf057e6f00358f51b
Author: Liu Kui <kui.liu at virtuozzo.com>
Date:   Thu Mar 27 22:45:52 2025 +0800

    fs/fuse kio: convert BUG_ON check to error handling
    
    The BUG_ON condition here is legitimate that can happen during fuse
    connection teardown. So a fatal error should be returned instead of
    crash.
    
    Fixes: 0f8ffab52203 ("fs/fuse kio: implement pcs_krpc - export kernel RPC to
    userspace")
    https://virtuozzo.atlassian.net/browse/VSTOR-102865
    
    Signed-off-by: Liu Kui <kui.liu at virtuozzo.com>
    Acked-by: Alexey Kuznetsov <kuznet at virtuozzo.com>
    
    Feature: fuse: kRPC - single RPC for kernel and userspace
---
 fs/fuse/kio/pcs/pcs_krpc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/kio/pcs/pcs_krpc.c b/fs/fuse/kio/pcs/pcs_krpc.c
index 115bd67aa0d2..323205a3e2df 100644
--- a/fs/fuse/kio/pcs/pcs_krpc.c
+++ b/fs/fuse/kio/pcs/pcs_krpc.c
@@ -486,7 +486,10 @@ static int pcs_krpc_ioctl_send_msg(struct pcs_krpc *krpc, struct pcs_krpc_ioc_se
 	chunk->type = KRPC_CHUNK_TYPE_MR;
 
 	chunk->mr = pcs_mr_get(&cc_from_krpc(krpc)->mrs, iocmsg->hdr_chunk.mr_id);
-	BUG_ON(!chunk->mr);
+	if (!chunk->mr) {
+		res = -ENXIO;
+		goto err_free_data_chunk;
+	}
 
 	kreq->hdr_buf = (char *) kmap(pcs_umem_page(chunk->mr->umem, chunk->addr));
 	kreq->hdr_kv.iov_base = kreq->hdr_buf;
@@ -595,7 +598,8 @@ static int pcs_krpc_ioctl_send_msg(struct pcs_krpc *krpc, struct pcs_krpc_ioc_se
 
 err_free_data_chunk:
 	kreq_release_data_chunks(kreq);
-	pcs_mr_put(kreq->hdr_chunk.mr);
+	if (kreq->hdr_chunk.mr)
+		pcs_mr_put(kreq->hdr_chunk.mr);
 
 err_free_kreq:
 	krpc_req_free(kreq);