Re: [PATCH 2/7] syscalls/fanotify20: Validate the generic error info

Implement some validation for the generic error info record emitted by
the kernel.  The error number is fs-specific but, well, we only support
ext4 for now anyway.

Signed-off-by: Gabriel Krisman Bertazi <redacted>
---
 .../kernel/syscalls/fanotify/fanotify20.c     | 59 ++++++++++++++++++-
 1 file changed, 58 insertions(+), 1 deletion(-)

diff --git a/testcases/kernel/syscalls/fanotify/fanotify20.c b/testcases/kernel/syscalls/fanotify/fanotify20.c
index 50531bd99cc9..fd5cfb8744f1 100644
--- a/testcases/kernel/syscalls/fanotify/fanotify20.c
+++ b/testcases/kernel/syscalls/fanotify/fanotify20.c

@@ -37,6 +37,14 @@

 #ifndef FAN_FS_ERROR
 #define FAN_FS_ERROR           0x00008000
+
+#define FAN_EVENT_INFO_TYPE_ERROR      4
+
+struct fanotify_event_info_error {
+       struct fanotify_event_info_header hdr;
+       __s32 error;
+       __u32 error_count;
+};
 #endif

 #define BUF_SIZE 256

@@ -47,11 +55,54 @@ int fd_notify;

 static const struct test_case {
        char *name;
+       int error;
+       unsigned int error_count;
        void (*trigger_error)(void);
        void (*prepare_fs)(void);
 } testcases[] = {
 };

+struct fanotify_event_info_header *get_event_info(
+                                       struct fanotify_event_metadata *event,
+                                       int info_type)
+{
+       struct fanotify_event_info_header *hdr = NULL;
+       char *start = (char *) event;
+       int off;
+
+       for (off = event->metadata_len; (off+sizeof(*hdr)) < event->event_len;
+            off += hdr->len) {
+               hdr = (struct fanotify_event_info_header *) &(start[off]);
+               if (hdr->info_type == info_type)
+                       return hdr;
+       }
+       return NULL;
+}
+
+#define get_event_info_error(event)                                    \
+       ((struct fanotify_event_info_error *)                           \
+        get_event_info((event), FAN_EVENT_INFO_TYPE_ERROR))