fsverity fix for 5.15-rc4

Fix an integer overflow when computing the Merkle tree layout of
 extremely large files, exposed by btrfs adding support for fs-verity.
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Merge tag 'fsverity-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt

Pull fsverity fix from Eric Biggers:
 "Fix an integer overflow when computing the Merkle tree layout of
  extremely large files, exposed by btrfs adding support for fs-verity"

* tag 'fsverity-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
  fs-verity: fix signed integer overflow with i_size near S64_MAX

fs/verity/enable.c

@@ -177,7 +177,7 @@ static int build_merkle_tree(struct file *filp,
 	 * (level 0) and ascending to the root node (level 'num_levels - 1').
 	 * Then at the end (level 'num_levels'), calculate the root hash.
 	 */
-	blocks = (inode->i_size + params->block_size - 1) >>
+	blocks = ((u64)inode->i_size + params->block_size - 1) >>
 		 params->log_blocksize;
 	for (level = 0; level <= params->num_levels; level++) {
 		err = build_merkle_tree_level(filp, level, blocks, params,

fs/verity/open.c

@@ -89,7 +89,7 @@ int fsverity_init_merkle_tree_params(struct merkle_tree_params *params,
 	 */
 
 	/* Compute number of levels and the number of blocks in each level */
-	blocks = (inode->i_size + params->block_size - 1) >> log_blocksize;
+	blocks = ((u64)inode->i_size + params->block_size - 1) >> log_blocksize;
 	pr_debug("Data is %lld bytes (%llu blocks)\n", inode->i_size, blocks);
 	while (blocks > 1) {
 		if (params->num_levels >= FS_VERITY_MAX_LEVELS) {