Patch "reiserfs: check directory items on read from disk" has been added to the 5.13-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    reiserfs: check directory items on read from disk

to the 5.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     reiserfs-check-directory-items-on-read-from-disk.patch
and it can be found in the queue-5.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9b8b45330e8f49b845f736e60e181e281f4e0e62
Author: Shreyansh Chouhan <chouhan.shreyansh630@xxxxxxxxx>
Date:   Fri Jul 9 20:59:29 2021 +0530

    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@xxxxxxxxx
    Reported-by: syzbot+c31a48e6702ccb3d64c9@xxxxxxxxxxxxxxxxxxxxxxxxx
    Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@xxxxxxxxx>
    Signed-off-by: Jan Kara <jack@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c
index 476a7ff49482..ef42729216d1 100644
--- a/fs/reiserfs/stree.c
+++ b/fs/reiserfs/stree.c
@@ -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;
@@ -454,11 +472,14 @@ 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))) {
-			reiserfs_warning(NULL, "reiserfs-5093",
-					 "item entry count seems wrong %h",
-					 ih);
-			return 0;
+		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);
 	}