[PATCH] ext4: fix kernel infoleak via ext4_extent_header
From: Anirudh Rayabharam <hidden>
Date: 2021-05-05 13:30:37
Initialize eh_generation of struct ext4_extent_header to prevent leaking info to userspace. Fixes KMSAN kernel-infoleak bug reported by syzbot at: http://syzkaller.appspot.com/bug?id=78e9ad0e6952a3ca16e8234724b2fa92d041b9b8 Reported-by: syzbot+2dcfeaf8cb49b05e8f1a@syzkaller.appspotmail.com Signed-off-by: Anirudh Rayabharam <redacted> --- fs/ext4/extents.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 77c84d6f1af6..677d4821bcc1 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c@@ -825,6 +825,7 @@ void ext4_ext_tree_init(handle_t *handle, struct inode *inode) eh->eh_entries = 0; eh->eh_magic = EXT4_EXT_MAGIC; eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0)); + eh->eh_generation = 0; ext4_mark_inode_dirty(handle, inode); }
@@ -1090,6 +1091,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0)); neh->eh_magic = EXT4_EXT_MAGIC; neh->eh_depth = 0; + neh->eh_generation = 0; /* move remainder of path[depth] to the new leaf */ if (unlikely(path[depth].p_hdr->eh_entries !=
@@ -1167,6 +1169,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, neh->eh_magic = EXT4_EXT_MAGIC; neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0)); neh->eh_depth = cpu_to_le16(depth - i); + neh->eh_generation = 0; fidx = EXT_FIRST_INDEX(neh); fidx->ei_block = border; ext4_idx_store_pblock(fidx, oldblock);
--
2.26.2