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* [PATCH] reiserfs: check directry items on read from disk
@ 2021-07-09 15:29 Shreyansh Chouhan
  2021-07-20  7:31 ` Shreyansh Chouhan
  0 siblings, 1 reply; 4+ messages in thread
From: Shreyansh Chouhan @ 2021-07-09 15:29 UTC (permalink / raw)
  To: rkovhaev, jack
  Cc: Shreyansh Chouhan, reiserfs-devel, linux-kernel,
	syzbot+c31a48e6702ccb3d64c9

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.

Reported-by: syzbot+c31a48e6702ccb3d64c9@syzkaller.appspotmail.com
Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>
---
 fs/reiserfs/stree.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

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);
 	}
-- 
2.31.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-07-29  5:06 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2021-07-09 15:29 [PATCH] reiserfs: check directry items on read from disk Shreyansh Chouhan
2021-07-20  7:31 ` Shreyansh Chouhan
2021-07-26  8:20   ` Jan Kara
2021-07-29  5:06     ` Shreyansh Chouhan

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