[Devel] [PATCH VZ10 v2] fs/fuse kio: replace zero-length array with flexible array syntax

[Kui Liu]

please discard this one, I didn't notice the v1 version had been committed. please use the incremental fix  instead ([PATCH VZ10] fs/fuse kio: move struct krpc_completion to the end of struct krpc_req)
________________________________
From: Liu Kui <kui.liu at virtuozzo.com>
Sent: 18 May 2026 12:20
To: devel at openvz.org <devel at openvz.org>
Cc: Alexey Kuznetsov <kuznet at virtuozzo.com>; Andrey Zaitsev <azaitsev at virtuozzo.com>; Konstantin Khorenko <khorenko at virtuozzo.com>; Kui Liu <kui.liu at virtuozzo.com>
Subject: [PATCH VZ10 v2] fs/fuse kio: replace zero-length array with flexible array syntax

With FORTIFY_SOURCE, memcpy to a zero-length array field is flagged
as field-spanning, causing kernel warning. Switch to the C99 flexible
array [] syntax to fix this.

Changes:
v1:
 - _data_buf[0] -> _data_buf[] in struct krpc_completion
 - sync_resp[0] -> sync_resp[] in struct pcs_cs_iohdr
 - nodes[0] -> nodes[] in struct pcs_cs_map_prop
 - cs[0] -> cs[] in struct pcs_cs_list
 - cs[0] -> cs[] in struct pcs_ioc_getmap

v2:
 - move struct krpc_completion to the end of struct krpc_req

Link: https://virtuozzo.atlassian.net/browse/VSTOR-130548

Signed-off-by: Liu Kui <kui.liu at virtuozzo.com>
---
 fs/fuse/kio/pcs/pcs_cs_prot.h | 4 ++--
 fs/fuse/kio/pcs/pcs_ioctl.h   | 2 +-
 fs/fuse/kio/pcs/pcs_krpc.h    | 6 +++---
 fs/fuse/kio/pcs/pcs_map.h     | 2 +-
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/fuse/kio/pcs/pcs_cs_prot.h b/fs/fuse/kio/pcs/pcs_cs_prot.h
index c72066de7be4..c524d28b551e 100644
--- a/fs/fuse/kio/pcs/pcs_cs_prot.h
+++ b/fs/fuse/kio/pcs/pcs_cs_prot.h
@@ -79,7 +79,7 @@ struct pcs_cs_iohdr {
                 u32                     fiemap_count;   /* Used only in FIEMAP request, limit on number of extents to return */
         };
         struct pcs_cs_sync_data sync;           /* Filled in all requests and responses */
-       struct pcs_cs_sync_resp sync_resp[0];   /* Used only in response to write/sync */
+       struct pcs_cs_sync_resp sync_resp[];    /* Used only in response to write/sync */
 } __attribute__((aligned(8)));

 static inline int pcs_cs_use_aligned_io(u32 storage_version)
@@ -171,7 +171,7 @@ struct pcs_cs_map_prop {
         u16                     chain_nodes;
         u16                     reserved;
         u32                     nnodes;
-       struct pcs_cs_node_desc nodes[0];
+       struct pcs_cs_node_desc nodes[];
 } __attribute__((aligned(8)));

 #define CS_OBJ_UNKNOWN          -1
diff --git a/fs/fuse/kio/pcs/pcs_ioctl.h b/fs/fuse/kio/pcs/pcs_ioctl.h
index fb22cf8a01b0..07a87d6507f3 100644
--- a/fs/fuse/kio/pcs/pcs_ioctl.h
+++ b/fs/fuse/kio/pcs/pcs_ioctl.h
@@ -74,7 +74,7 @@ struct pcs_ioc_getmap
         /* TODO: cs array is only for OUT ? */
         u32                     cs_cnt;         /* The number of CS (including root) entries that follows */
         u32                     cs_max;         /* Max number of CS (including root) entries requested */
-       struct pcs_cs_info      cs[0];          /* Array of CS including root */
+       struct pcs_cs_info      cs[];           /* Array of CS including root */
 };

 #define PCS_IOC_NOCSUMONREAD    _IOW('V',3,u32)
diff --git a/fs/fuse/kio/pcs/pcs_krpc.h b/fs/fuse/kio/pcs/pcs_krpc.h
index 6a090ef66185..92dae58ef43b 100644
--- a/fs/fuse/kio/pcs/pcs_krpc.h
+++ b/fs/fuse/kio/pcs/pcs_krpc.h
@@ -99,7 +99,7 @@ struct krpc_completion {

         void            *private;
         int                     data_len;
-       u8                      _data_buf[0];
+       u8                      _data_buf[];
 };

 #define KRPC_MAX_DATA_PAGES                     256
@@ -129,11 +129,11 @@ struct krpc_req {
         int nr_data_bvecs;
         struct bio_vec data_bvecs[KRPC_MAX_DATA_PAGES];

-       struct krpc_completion completion;
-
         u32                         gen;
         struct llist_node           llist_link;
         struct pcs_krpc_ioc_sendmsg iocmsg;
+
+       struct krpc_completion completion;
 };

 static inline u32 pcs_krpc_msg_size(u32 size, u8 flags)
diff --git a/fs/fuse/kio/pcs/pcs_map.h b/fs/fuse/kio/pcs/pcs_map.h
index bf8a0e7177d0..788a8cb16d8e 100644
--- a/fs/fuse/kio/pcs/pcs_map.h
+++ b/fs/fuse/kio/pcs/pcs_map.h
@@ -127,7 +127,7 @@ struct pcs_cs_list
         int                     write_timeout;
         int                     nsrv;
         PCS_MAP_VERSION_T       version;                /* version inherented from map */
-       struct pcs_cs_record    cs[0];
+       struct pcs_cs_record    cs[];
 };

 /* TODO, LOCKING!!!!!
--
2.39.5 (Apple Git-154)

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openvz.org/pipermail/devel/attachments/20260518/a4f8530a/attachment-0001.html>