From: Anirudh Rayabharam mail@anirudhrb.com
commit ce3aba43599f0b50adbebff133df8d08a3d5fffe upstream.
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
Cc: stable@kernel.org Reported-by: syzbot+2dcfeaf8cb49b05e8f1a@syzkaller.appspotmail.com Fixes: a86c61812637 ("[PATCH] ext3: add extent map support") Signed-off-by: Anirudh Rayabharam mail@anirudhrb.com Link: https://lore.kernel.org/r/20210506185655.7118-1-mail@anirudhrb.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/ext4/extents.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -858,6 +858,7 @@ int ext4_ext_tree_init(handle_t *handle, 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); return 0; } @@ -1114,6 +1115,7 @@ static int ext4_ext_split(handle_t *hand 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 != @@ -1191,6 +1193,7 @@ static int ext4_ext_split(handle_t *hand 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);