Merge tag 'exfat-for-6.14-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat

Pull exfat fixes from Namjae Jeon:

 - Optimize new cluster allocation by correctly find empty entry slot

 - Add a check to prevent excessive bitmap clearing due to invalid
   data size of file/dir entry

 - Fix incorrect error return for zero-byte writes

* tag 'exfat-for-6.14-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat:
  exfat: add a check for invalid data size
  exfat: short-circuit zero-byte writes in exfat_file_write_iter
  exfat: fix soft lockup in exfat_clear_bitmap
  exfat: fix just enough dentries but allocate a new cluster to dir

Author: torvalds

fs/exfat/balloc.c

@@ -141,7 +141,7 @@ int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
 	return 0;
 }
 
-void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
+int exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
 {
 	int i, b;
 	unsigned int ent_idx;
@@ -150,13 +150,17 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
 	struct exfat_mount_options *opts = &sbi->options;
 
 	if (!is_valid_cluster(sbi, clu))
-		return;
+		return -EIO;
 
 	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
 
+	if (!test_bit_le(b, sbi->vol_amap[i]->b_data))
+		return -EIO;
+
 	clear_bit_le(b, sbi->vol_amap[i]->b_data);
+
 	exfat_update_bh(sbi->vol_amap[i], sync);
 
 	if (opts->discard) {
@@ -171,6 +175,8 @@ void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
 			opts->discard = 0;
 		}
 	}
+
+	return 0;
 }
 
 /*

fs/exfat/exfat_fs.h

@@ -456,7 +456,7 @@ int exfat_count_num_clusters(struct super_block *sb,
 int exfat_load_bitmap(struct super_block *sb);
 void exfat_free_bitmap(struct exfat_sb_info *sbi);
 int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync);
-void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync);
+int exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync);
 unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu);
 int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count);
 int exfat_trim_fs(struct inode *inode, struct fstrim_range *range);

fs/exfat/fatent.c

@@ -175,6 +175,7 @@ static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain
 		BITMAP_OFFSET_SECTOR_INDEX(sb, CLUSTER_TO_BITMAP_ENT(clu));
 
 	if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
+		int err;
 		unsigned int last_cluster = p_chain->dir + p_chain->size - 1;
 		do {
 			bool sync = false;
@@ -189,7 +190,9 @@ static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain
 				cur_cmap_i = next_cmap_i;
 			}
 
-			exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
+			err = exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
+			if (err)
+				break;
 			clu++;
 			num_clusters++;
 		} while (num_clusters < p_chain->size);
@@ -210,12 +213,13 @@ static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain
 				cur_cmap_i = next_cmap_i;
 			}
 
-			exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode)));
+			if (exfat_clear_bitmap(inode, clu, (sync && IS_DIRSYNC(inode))))
+				break;
 			clu = n_clu;
 			num_clusters++;
 
 			if (err)
-				goto dec_used_clus;
+				break;
 
 			if (num_clusters >= sbi->num_clusters - EXFAT_FIRST_CLUSTER) {
 				/*
@@ -229,7 +233,6 @@ static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain
 		} while (clu != EXFAT_EOF_CLUSTER);
 	}
 
-dec_used_clus:
 	sbi->used_clusters -= num_clusters;
 	return 0;
 }

fs/exfat/file.c

@@ -587,7 +587,7 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter)
 	valid_size = ei->valid_size;
 
 	ret = generic_write_checks(iocb, iter);
-	if (ret < 0)
+	if (ret <= 0)
 		goto unlock;
 
 	if (iocb->ki_flags & IOCB_DIRECT) {

fs/exfat/namei.c

@@ -232,7 +232,7 @@ static int exfat_search_empty_slot(struct super_block *sb,
 		dentry = 0;
 	}
 
-	while (dentry + num_entries < total_entries &&
+	while (dentry + num_entries <= total_entries &&
 	       clu.dir != EXFAT_EOF_CLUSTER) {
 		i = dentry & (dentries_per_clu - 1);
 
@@ -646,6 +646,11 @@ static int exfat_find(struct inode *dir, struct qstr *qname,
 	info->valid_size = le64_to_cpu(ep2->dentry.stream.valid_size);
 	info->size = le64_to_cpu(ep2->dentry.stream.size);
 
+	if (unlikely(EXFAT_B_TO_CLU_ROUND_UP(info->size, sbi) > sbi->used_clusters)) {
+		exfat_fs_error(sb, "data size is invalid(%lld)", info->size);
+		return -EIO;
+	}
+
 	info->start_clu = le32_to_cpu(ep2->dentry.stream.start_clu);
 	if (!is_valid_cluster(sbi, info->start_clu) && info->size) {
 		exfat_warn(sb, "start_clu is invalid cluster(0x%x)",