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exfat: fix overflow in cluster-to-dentry conversion

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The cluster-to-dentry calculation is performed as u32 and may overflow
and wrap around on large volumes. This can result in an incorrect
max_dentries value, causing readdir to stop early and omit directory
entries.

Cast nr_clusters to u64 before shifting to avoid the overflow.

Signed-off-by: Yang Wen <anmuxixixi@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Yang Wen
2026-08-06 22:06:09 +09:00
committed by Namjae Jeon
parent 0901a71e8c
commit 0eb24ad05a
2 changed files with 3 additions and 3 deletions
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fs/exfat/dir.c
+1 -1
View File
@@ -87,7 +87,7 @@ static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_ent
exfat_bytes_to_cluster(sbi, i_size_read(inode)), ei->flags);
dentries_per_clu = sbi->dentries_per_clu;
max_dentries = min(MAX_EXFAT_DENTRIES,
max_dentries = (unsigned int)min_t(u64, MAX_EXFAT_DENTRIES,
exfat_cluster_to_dentries(sbi, sbi->num_clusters));
clu_offset = exfat_dentries_to_cluster(sbi, dentry);
fs/exfat/exfat_fs.h
+2 -2
View File
@@ -487,10 +487,10 @@ static inline u32 exfat_dentries_to_bytes(u32 dentry)
/*
* helpers for cluster size to dentry size conversion.
*/
static inline u32 exfat_cluster_to_dentries(struct exfat_sb_info *sbi,
static inline u64 exfat_cluster_to_dentries(struct exfat_sb_info *sbi,
u32 nr_clusters)
{
return nr_clusters << (sbi->cluster_size_bits - DENTRY_SIZE_BITS);
return (u64)nr_clusters << (sbi->cluster_size_bits - DENTRY_SIZE_BITS);
}
static inline u32 exfat_dentries_to_cluster(struct exfat_sb_info *sbi,