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staging: erofs: fix an error handling in erofs_readdir() 

Richard observed a forever loop of erofs_read_raw_page() [1]
which can be generated by forcely setting ->u.i_blkaddr
to 0xdeadbeef (as my understanding block layer can
handle access beyond end of device correctly).

After digging into that, it seems the problem is highly
related with directories and then I found the root cause
is an improper error handling in erofs_readdir().

Let's fix it now.

[1] https://lore.kernel.org/r/1163995781.68824.1566084358245.JavaMail.zimbra@nod.at/

Reported-by: Richard Weinberger <richard@nod.at>
Fixes: 3aa8ec716e ("staging: erofs: add directory operations")
Cc: <stable@vger.kernel.org> # 4.19+
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190818125457.25906-1-hsiangkao@aol.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Gao Xiang 2019-08-18 20:54:57 +08:00 committed by Greg Kroah-Hartman
parent a64d9493f5
commit acb383f1dc
1 changed files with 9 additions and 2 deletions
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11
drivers/staging/erofs/dir.c
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@ -82,8 +82,15 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
unsigned int nameoff, maxsize;
dentry_page = read_mapping_page(mapping, i, NULL);
if (IS_ERR(dentry_page))
continue;
if (dentry_page == ERR_PTR(-ENOMEM)) {
err = -ENOMEM;
break;
} else if (IS_ERR(dentry_page)) {
errln("fail to readdir of logical block %u of nid %llu",
i, EROFS_V(dir)->nid);
err = -EFSCORRUPTED;
break;
}
de = (struct erofs_dirent *)kmap(dentry_page);