reiserfs: add check for an invalid ih_entry_count

when directory item has an invalid value set for ih_entry_count it might trigger use-after-free or out-of-bounds read in bin_search_in_dir_item() ih_entry_count * IH_SIZE for directory item should not be larger than ih_item_len Link: https://lore.kernel.org/r/[email protected] Reported-and-tested-by: [email protected] Link: https://syzkaller.appspot.com/bug?extid=83b6f7cf9922cae5c4d7 Signed-off-by: Rustam Kovhaev <[email protected]> Signed-off-by: Jan Kara <[email protected]>
zandrey · Nov 26, 2020 · d24396c · d24396c
1 parent 8fca3c8
commit d24396c
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c
@@ -454,6 +454,12 @@ 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;
+		}
 		prev_location = ih_location(ih);
 	}