From f6e6652d7c9251236fc1ecc6cece36104c7af15b Mon Sep 17 00:00:00 2001 From: Peter Wu Date: Tue, 6 Jan 2015 18:48:08 +0100 Subject: [PATCH] block/dmg: validate chunk size to avoid overflow Previously the chunk size was not checked, allowing for a large memory allocation. This patch checks whether the chunks size is within the resource fork length, and whether the resource fork is below the trailer of the dmg file. Signed-off-by: Peter Wu Reviewed-by: John Snow Message-id: 1420566495-13284-6-git-send-email-peter@lekensteyn.nl Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/dmg.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/block/dmg.c b/block/dmg.c index 4f56227fc5..5c2c2c231d 100644 --- a/block/dmg.c +++ b/block/dmg.c @@ -317,7 +317,7 @@ static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds, ret = read_uint32(bs, offset, &count); if (ret < 0) { goto fail; - } else if (count == 0) { + } else if (count == 0 || count > info_end - offset) { ret = -EINVAL; goto fail; } @@ -377,6 +377,11 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags, if (ret < 0) { goto fail; } + if (rsrc_fork_offset >= offset || + rsrc_fork_length > offset - rsrc_fork_offset) { + ret = -EINVAL; + goto fail; + } if (rsrc_fork_length != 0) { ret = dmg_read_resource_fork(bs, &ds, rsrc_fork_offset, rsrc_fork_length); -- GitLab