exofs: Avoid VLA in structures

index 3c6a9c156b7a..cfa862ea19d2 100644
@@ -146,68 +146,82 @@ int  _ore_get_io_state(struct ore_layout *layout,
 			struct ore_io_state **pios)
 {
 	struct ore_io_state *ios;
-	struct page **pages;
-	struct osd_sg_entry *sgilist;
+	size_t size_ios, size_extra, size_total;
+	void *ios_extra;
+
+	/*
+	 * The desired layout looks like this, with the extra_allocation
+	 * items pointed at from fields within ios or per_dev:
+
 	struct __alloc_all_io_state {
 		struct ore_io_state ios;
 		struct ore_per_dev_state per_dev[numdevs];
 		union {
 			struct osd_sg_entry sglist[sgs_per_dev * numdevs];
 			struct page *pages[num_par_pages];
-		};
-	} *_aios;
-
-	if (likely(sizeof(*_aios) <= PAGE_SIZE)) {
-		_aios = kzalloc(sizeof(*_aios), GFP_KERNEL);
-		if (unlikely(!_aios)) {
-			ORE_DBGMSG("Failed kzalloc bytes=%zd\n",
-				   sizeof(*_aios));
+		} extra_allocation;
+	} whole_allocation;
+
+	*/
+
+	/* This should never happen, so abort early if it ever does. */
+	if (sgs_per_dev && num_par_pages) {
+		ORE_DBGMSG("Tried to use both pages and sglist\n");
+		*pios = NULL;
+		return -EINVAL;
+	}
+
+	if (numdevs > (INT_MAX - sizeof(*ios)) /
+		       sizeof(struct ore_per_dev_state))
+		return -ENOMEM;
+	size_ios = sizeof(*ios) + sizeof(struct ore_per_dev_state) * numdevs;
+
+	if (sgs_per_dev * numdevs > INT_MAX / sizeof(struct osd_sg_entry))
+		return -ENOMEM;
+	if (num_par_pages > INT_MAX / sizeof(struct page *))
+		return -ENOMEM;
+	size_extra = max(sizeof(struct osd_sg_entry) * (sgs_per_dev * numdevs),
+			 sizeof(struct page *) * num_par_pages);
+
+	size_total = size_ios + size_extra;
+
+	if (likely(size_total <= PAGE_SIZE)) {
+		ios = kzalloc(size_total, GFP_KERNEL);
+		if (unlikely(!ios)) {
+			ORE_DBGMSG("Failed kzalloc bytes=%zd\n", size_total);
 			*pios = NULL;
 			return -ENOMEM;
 		}
-		pages = num_par_pages ? _aios->pages : NULL;
-		sgilist = sgs_per_dev ? _aios->sglist : NULL;
-		ios = &_aios->ios;
+		ios_extra = (char *)ios + size_ios;
 	} else {
-		struct __alloc_small_io_state {
-			struct ore_io_state ios;
-			struct ore_per_dev_state per_dev[numdevs];
-		} *_aio_small;
-		union __extra_part {
-			struct osd_sg_entry sglist[sgs_per_dev * numdevs];
-			struct page *pages[num_par_pages];
-		} *extra_part;
-
-		_aio_small = kzalloc(sizeof(*_aio_small), GFP_KERNEL);
-		if (unlikely(!_aio_small)) {
+		ios = kzalloc(size_ios, GFP_KERNEL);
+		if (unlikely(!ios)) {
 			ORE_DBGMSG("Failed alloc first part bytes=%zd\n",
-				   sizeof(*_aio_small));
+				   size_ios);
 			*pios = NULL;
 			return -ENOMEM;
 		}
-		extra_part = kzalloc(sizeof(*extra_part), GFP_KERNEL);
-		if (unlikely(!extra_part)) {
+		ios_extra = kzalloc(size_extra, GFP_KERNEL);
+		if (unlikely(!ios_extra)) {
 			ORE_DBGMSG("Failed alloc second part bytes=%zd\n",
-				   sizeof(*extra_part));
-			kfree(_aio_small);
+				   size_extra);
+			kfree(ios);
 			*pios = NULL;
 			return -ENOMEM;
 		}
 
-		pages = num_par_pages ? extra_part->pages : NULL;
-		sgilist = sgs_per_dev ? extra_part->sglist : NULL;
 		/* In this case the per_dev[0].sgilist holds the pointer to
 		 * be freed
 		 */
-		ios = &_aio_small->ios;
 		ios->extra_part_alloc = true;
 	}
 
-	if (pages) {
-		ios->parity_pages = pages;
+	if (num_par_pages) {
+		ios->parity_pages = ios_extra;
 		ios->max_par_pages = num_par_pages;
 	}
-	if (sgilist) {
+	if (sgs_per_dev) {
+		struct osd_sg_entry *sgilist = ios_extra;
 		unsigned d;
 
 		for (d = 0; d < numdevs; ++d) {

116 lines not on this page · raw message

index 179cd5c2f52a..fabd15e482be 100644
@@ -549,27 +549,26 @@ static int exofs_devs_2_odi(struct exofs_dt_device_info *dt_dev,
 static int __alloc_dev_table(struct exofs_sb_info *sbi, unsigned numdevs,
 		      struct exofs_dev **peds)
 {
-	struct __alloc_ore_devs_and_exofs_devs {
-		/* Twice bigger table: See exofs_init_comps() and comment at
-		 * exofs_read_lookup_dev_table()
-		 */
-		struct ore_dev *oreds[numdevs * 2 - 1];
-		struct exofs_dev eds[numdevs];
-	} *aoded;
+	/* Twice bigger table: See exofs_init_comps() and comment at
+	 * exofs_read_lookup_dev_table()
+	 */
+	const size_t numores = numdevs * 2 - 1;
 	struct exofs_dev *eds;
 	unsigned i;
 
-	aoded = kzalloc(sizeof(*aoded), GFP_KERNEL);
-	if (unlikely(!aoded)) {
+	sbi->oc.ods = kzalloc(numores * sizeof(struct ore_dev *) +
+			      numdevs * sizeof(struct exofs_dev), GFP_KERNEL);
+	if (unlikely(!sbi->oc.ods)) {
 		EXOFS_ERR("ERROR: failed allocating Device array[%d]\n",
 			  numdevs);
 		return -ENOMEM;
 	}
 
-	sbi->oc.ods = aoded->oreds;
-	*peds = eds = aoded->eds;
+	/* Start of allocated struct exofs_dev entries */
+	*peds = eds = (void *)sbi->oc.ods[numores];
+	/* Initialize pointers into struct exofs_dev */
 	for (i = 0; i < numdevs; ++i)
-		aoded->oreds[i] = &eds[i].ored;
+		sbi->oc.ods[i] = &eds[i].ored;
 	return 0;
 }