File 0121-mkfs.btrfs-write-zeroes-instead-on-uninitialized-dat.patch of Package btrfsprogs
From 6b8dacb969d0e4c61c4a2a6f9d6144e934595f73 Mon Sep 17 00:00:00 2001 From: Sergei Trofimovich <slyfox@gentoo.org> Date: Sat, 4 Jun 2011 11:19:21 +0300 Subject: [PATCH 21/28] mkfs.btrfs: write zeroes instead on uninitialized data. Found by valgrind: ==8968== Use of uninitialised value of size 8 ==8968== at 0x41CE7D: crc32c_le (crc32c.c:98) ==8968== by 0x40A1D0: csum_tree_block_size (disk-io.c:82) ==8968== by 0x40A2D4: csum_tree_block (disk-io.c:105) ==8968== by 0x40A7D6: write_tree_block (disk-io.c:241) ==8968== by 0x40ACEE: __commit_transaction (disk-io.c:354) ==8968== by 0x40AE9E: btrfs_commit_transaction (disk-io.c:385) ==8968== by 0x42CF66: make_image (mkfs.c:1061) ==8968== by 0x42DE63: main (mkfs.c:1410) ==8968== Uninitialised value was created by a stack allocation ==8968== at 0x42B5FB: add_inode_items (mkfs.c:493) 1. On-disk inode format has reserved (and thus, random at alloc time) fields: btrfs_inode_item: __le64 reserved[4] 2. Sometimes extents are created on disk without writing data there. (Or at least not all data is written there). Kernel code always had it kzalloc'ed. Zero them all. Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> Signed-off-by: Hugo Mills <hugo@carfax.org.uk> --- extent_io.c | 1 + mkfs.c | 7 +++++++ 2 files changed, 8 insertions(+), 0 deletions(-) diff --git a/extent_io.c b/extent_io.c index 70fecbb..8f0a876 100644 --- a/extent_io.c +++ b/extent_io.c @@ -568,6 +568,7 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, BUG(); return NULL; } + memset(eb, 0, sizeof(struct extent_buffer) + blocksize); eb->start = bytenr; eb->len = blocksize; diff --git a/mkfs.c b/mkfs.c index 5e483dc..428ec18 100644 --- a/mkfs.c +++ b/mkfs.c @@ -411,6 +411,13 @@ static int fill_inode_item(struct btrfs_trans_handle *trans, u64 blocks = 0; u64 sectorsize = root->sectorsize; + /* + * btrfs_inode_item has some reserved fields + * and represents on-disk inode entry, so + * zero everything to prevent information leak + */ + memset(dst, 0, sizeof (*dst)); + btrfs_set_stack_inode_generation(dst, trans->transid); btrfs_set_stack_inode_size(dst, src->st_size); btrfs_set_stack_inode_nbytes(dst, 0); -- 1.7.5.2.353.g5df3e
