[3/3] f2fs: avoid garbage lenghs in dentries
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Message ID 1455332195-76333-3-git-send-email-jaegeuk@kernel.org
State New
Headers show

Commit Message

Jaegeuk Kim Feb. 13, 2016, 2:56 a.m. UTC
This patch fixes to eliminate garbage name lengths in dentries in order
to provide correct answers of readdir.

For example, if a valid dentry consists of:
 bitmap : 1   1 1 1
 len    : 32  0 x 0,

readdir can start with second bit_pos having len = 0.
Or, it can start with third bit_pos having garbage.

In both of cases, we should avoid to try filling dentries.
So, this patch not only removes any garbage length, but also avoid entering
zero length case in readdir.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/dir.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Patch
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diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 8950fc3..ca41b2a 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -511,8 +511,12 @@  void f2fs_update_dentry(nid_t ino, umode_t mode, struct f2fs_dentry_ptr *d,
 	memcpy(d->filename[bit_pos], name->name, name->len);
 	de->ino = cpu_to_le32(ino);
 	set_de_type(de, mode);
-	for (i = 0; i < slots; i++)
+	for (i = 0; i < slots; i++) {
 		test_and_set_bit_le(bit_pos + i, (void *)d->bitmap);
+		/* avoid wrong garbage data for readdir */
+		if (i)
+			(de + i)->name_len = 0;
+	}
 }
 
 /*
@@ -792,6 +796,12 @@  bool f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
 			break;
 
 		de = &d->dentry[bit_pos];
+		if (de->name_len == 0) {
+			bit_pos++;
+			ctx->pos = start_pos + bit_pos;
+			continue;
+		}
+
 		if (de->file_type < F2FS_FT_MAX)
 			d_type = f2fs_filetype_table[de->file_type];
 		else