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exfat: fix out-of-bounds access of directory entries

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In the case of the directory size is greater than or equal to
the cluster size, if start_clu becomes an EOF cluster(an invalid
cluster) due to file system corruption, then the directory entry
where ei->hint_femp.eidx hint is outside the directory, resulting
in an out-of-bounds access, which may cause further file system
corruption.

This commit adds a check for start_clu, if it is an invalid cluster,
the file or directory will be treated as empty.

Cc: stable@vger.kernel.org
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Co-developed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Yuezhang Mo 2024-10-28 11:23:36 +08:00 committed by Namjae Jeon
parent 9f16d5e6f2
commit 184fa506e3
1 changed files with 16 additions and 4 deletions
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20
fs/exfat/namei.c
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@ -637,14 +637,26 @@ static int exfat_find(struct inode *dir, struct qstr *qname,
info->size = le64_to_cpu(ep2->dentry.stream.valid_size);
info->valid_size = le64_to_cpu(ep2->dentry.stream.valid_size);
info->size = le64_to_cpu(ep2->dentry.stream.size);
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)",
info->start_clu);
info->size = 0;
info->valid_size = 0;
}
if (info->valid_size > info->size) {
exfat_warn(sb, "valid_size(%lld) is greater than size(%lld)",
info->valid_size, info->size);
info->valid_size = info->size;
}
if (info->size == 0) {
info->flags = ALLOC_NO_FAT_CHAIN;
info->start_clu = EXFAT_EOF_CLUSTER;
} else {
} else
info->flags = ep2->dentry.stream.flags;
info->start_clu =
le32_to_cpu(ep2->dentry.stream.start_clu);
}
exfat_get_entry_time(sbi, &info->crtime,
ep->dentry.file.create_tz,