From: Shreyansh Chouhan chouhan.shreyansh630@gmail.com
[ 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... Reported-by: syzbot+c31a48e6702ccb3d64c9@syzkaller.appspotmail.com Signed-off-by: Shreyansh Chouhan chouhan.shreyansh630@gmail.com Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Sasha Levin sashal@kernel.org --- 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 5229038852ca..4ebad6781b0e 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); }