zdb_il: use flex array member to access ZIL records

In 6f50f8e we added flex arrays to lr_XX_t structs to silence kernel
bounds check warnings. Userspace code was mostly not updated to use them
though.

It seems that in the right circumstances, compilers can get confused
about sizes in the same way, and throw warnings. This commits switch
those uses over to use the flex array fields also.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Sponsored-by: https://despairlabs.com/sponsor/
Closes #16832

cmd/zdb/zdb_il.c

@@ -67,19 +67,19 @@ zil_prt_rec_create(zilog_t *zilog, int txtype, const void *arg)
 	const lr_create_t *lrc = arg;
 	const _lr_create_t *lr = &lrc->lr_create;
 	time_t crtime = lr->lr_crtime[0];
-	char *name, *link;
+	const char *name, *link;
 	lr_attr_t *lrattr;
 
-	name = (char *)(lr + 1);
+	name = (const char *)&lrc->lr_data[0];
 
 	if (lr->lr_common.lrc_txtype == TX_CREATE_ATTR ||
 	    lr->lr_common.lrc_txtype == TX_MKDIR_ATTR) {
-		lrattr = (lr_attr_t *)(lr + 1);
+		lrattr = (lr_attr_t *)&lrc->lr_data[0];
 		name += ZIL_XVAT_SIZE(lrattr->lr_attr_masksize);
 	}
 
 	if (txtype == TX_SYMLINK) {
-		link = name + strlen(name) + 1;
+		link = (const char *)&lrc->lr_data[strlen(name) + 1];
 		(void) printf("%s%s -> %s\n", tab_prefix, name, link);
 	} else if (txtype != TX_MKXATTR) {
 		(void) printf("%s%s\n", tab_prefix, name);
@@ -104,7 +104,7 @@ zil_prt_rec_remove(zilog_t *zilog, int txtype, const void *arg)
 	const lr_remove_t *lr = arg;
 
 	(void) printf("%sdoid %llu, name %s\n", tab_prefix,
-	    (u_longlong_t)lr->lr_doid, (char *)(lr + 1));
+	    (u_longlong_t)lr->lr_doid, (const char *)&lr->lr_data[0]);
 }
 
 static void
@@ -115,7 +115,7 @@ zil_prt_rec_link(zilog_t *zilog, int txtype, const void *arg)
 
 	(void) printf("%sdoid %llu, link_obj %llu, name %s\n", tab_prefix,
 	    (u_longlong_t)lr->lr_doid, (u_longlong_t)lr->lr_link_obj,
-	    (char *)(lr + 1));
+	    (const char *)&lr->lr_data[0]);
 }
 
 static void
@@ -124,8 +124,8 @@ zil_prt_rec_rename(zilog_t *zilog, int txtype, const void *arg)
 	(void) zilog, (void) txtype;
 	const lr_rename_t *lrr = arg;
 	const _lr_rename_t *lr = &lrr->lr_rename;
-	char *snm = (char *)(lr + 1);
-	char *tnm = snm + strlen(snm) + 1;
+	const char *snm = (const char *)&lrr->lr_data[0];
+	const char *tnm = (const char *)&lrr->lr_data[strlen(snm) + 1];
 
 	(void) printf("%ssdoid %llu, tdoid %llu\n", tab_prefix,
 	    (u_longlong_t)lr->lr_sdoid, (u_longlong_t)lr->lr_tdoid);
@@ -211,7 +211,7 @@ zil_prt_rec_write(zilog_t *zilog, int txtype, const void *arg)
 
 		/* data is stored after the end of the lr_write record */
 		data = abd_alloc(lr->lr_length, B_FALSE);
-		abd_copy_from_buf(data, lr + 1, lr->lr_length);
+		abd_copy_from_buf(data, &lr->lr_data[0], lr->lr_length);
 	}
 
 	(void) printf("%s", tab_prefix);
@@ -309,7 +309,7 @@ zil_prt_rec_setsaxattr(zilog_t *zilog, int txtype, const void *arg)
 	(void) zilog, (void) txtype;
 	const lr_setsaxattr_t *lr = arg;
 
-	char *name = (char *)(lr + 1);
+	const char *name = (const char *)&lr->lr_data[0];
 	(void) printf("%sfoid %llu\n", tab_prefix,
 	    (u_longlong_t)lr->lr_foid);
 
@@ -318,7 +318,7 @@ zil_prt_rec_setsaxattr(zilog_t *zilog, int txtype, const void *arg)
 		(void) printf("%sXAT_VALUE  NULL\n", tab_prefix);
 	} else {
 		(void) printf("%sXAT_VALUE  ", tab_prefix);
-		char *val = name + (strlen(name) + 1);
+		const char *val = (const char *)&lr->lr_data[strlen(name) + 1];
 		for (int i = 0; i < lr->lr_size; i++) {
 			(void) printf("%c", *val);
 			val++;