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Commit 17d7c9c9 authored by Shreyansh Chouhan's avatar Shreyansh Chouhan Committed by Greg Kroah-Hartman
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reiserfs: check directory items on read from disk 

[ Upstream commit 13d257503c0930010ef9eed78b689cec417ab741 ]

While verifying the leaf item that we read from the disk, reiserfs
doesn't check the directory items, this could cause a crash when we
read a directory item from the disk that has an invalid deh_location.

This patch adds a check to the directory items read from the disk that
does a bounds check on deh_location for the directory entries. Any
directory entry header with a directory entry offset greater than the
item length is considered invalid.

Link: https://lore.kernel.org/r/20210709152929.766363-1-chouhan.shreyansh630@gmail.com


Reported-by: default avatar <syzbot+c31a48e6702ccb3d64c9@syzkaller.appspotmail.com>
Signed-off-by: default avatarShreyansh Chouhan <chouhan.shreyansh630@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent bcad6ece

fs/reiserfs/stree.c

+26 −5
Original line number Diff line number Diff line
@@ -387,6 +387,24 @@ void pathrelse(struct treepath *search_path) 
	search_path->path_length = ILLEGAL_PATH_ELEMENT_OFFSET;

}



static int has_valid_deh_location(struct buffer_head *bh, struct item_head *ih)

{

	struct reiserfs_de_head *deh;

	int i;



	deh = B_I_DEH(bh, ih);

	for (i = 0; i < ih_entry_count(ih); i++) {

		if (deh_location(&deh[i]) > ih_item_len(ih)) {

			reiserfs_warning(NULL, "reiserfs-5094",

					 "directory entry location seems wrong %h",

					 &deh[i]);

			return 0;

		}

	}



	return 1;

}



static int is_leaf(char *buf, int blocksize, struct buffer_head *bh)

{

	struct block_head *blkh;
@@ -454,12 +472,15 @@ static int is_leaf(char *buf, int blocksize, struct buffer_head *bh) 
					 "(second one): %h", ih);

			return 0;

		}

		if (is_direntry_le_ih(ih) && (ih_item_len(ih) < (ih_entry_count(ih) * IH_SIZE))) {

		if (is_direntry_le_ih(ih)) {

			if (ih_item_len(ih) < (ih_entry_count(ih) * IH_SIZE)) {

				reiserfs_warning(NULL, "reiserfs-5093",

						 "item entry count seems wrong %h",

						 ih);

				return 0;

			}

			return has_valid_deh_location(bh, ih);

		}

		prev_location = ih_location(ih);

	}