From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53377) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1defYY-00041k-NH for qemu-devel@nongnu.org; Mon, 07 Aug 2017 06:46:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1defYX-0004Q2-CE for qemu-devel@nongnu.org; Mon, 07 Aug 2017 06:46:42 -0400 Date: Mon, 7 Aug 2017 12:46:30 +0200 From: Kevin Wolf Message-ID: <20170807104630.GA6578@localhost.localdomain> References: <85fe374c783a6d659bc86aa7f15d5f442b9d7a45.1502075213.git.jcody@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <85fe374c783a6d659bc86aa7f15d5f442b9d7a45.1502075213.git.jcody@redhat.com> Subject: Re: [Qemu-devel] [Qemu-block] [PATCH 1/2] block/vhdx: check error return of bdrv_getlength() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jeff Cody Cc: qemu-devel@nongnu.org, armbru@redhat.com, qemu-block@nongnu.org Am 07.08.2017 um 05:08 hat Jeff Cody geschrieben: > Calls to bdrv_getlength() were not checking for error. In vhdx.c, this > can lead to truncating an image file, so it is a definite bug. In > vhdx-log.c, the path for improper behavior is less clear, but it is best > to check in any case. > > Reported-by: Markus Armbruster > Signed-off-by: Jeff Cody > --- > block/vhdx-log.c | 20 ++++++++++++++++---- > block/vhdx.c | 9 ++++++++- > 2 files changed, 24 insertions(+), 5 deletions(-) > > diff --git a/block/vhdx-log.c b/block/vhdx-log.c > index 01278f3..fd4e7af 100644 > --- a/block/vhdx-log.c > +++ b/block/vhdx-log.c > @@ -491,6 +491,7 @@ static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s, > uint32_t cnt, sectors_read; > uint64_t new_file_size; > void *data = NULL; > + int64_t file_length; > VHDXLogDescEntries *desc_entries = NULL; > VHDXLogEntryHeader hdr_tmp = { 0 }; > > @@ -510,10 +511,15 @@ static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s, > if (ret < 0) { > goto exit; > } > + file_length = bdrv_getlength(bs->file->bs); > + if (file_length < 0) { > + ret = file_length; > + goto exit; > + } > /* if the log shows a FlushedFileOffset larger than our current file > * size, then that means the file has been truncated / corrupted, and > * we must refused to open it / use it */ > - if (hdr_tmp.flushed_file_offset > bdrv_getlength(bs->file->bs)) { > + if (hdr_tmp.flushed_file_offset > file_length) { > ret = -EINVAL; > goto exit; > } > @@ -543,7 +549,7 @@ static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s, > goto exit; > } > } > - if (bdrv_getlength(bs->file->bs) < desc_entries->hdr.last_file_offset) { > + if (file_length < desc_entries->hdr.last_file_offset) { > new_file_size = desc_entries->hdr.last_file_offset; > if (new_file_size % (1024*1024)) { > /* round up to nearest 1MB boundary */ The vhdx_log_flush() part looks good, but it made me notice a bdrv_flush() in the same function where the return value isn't checked. I'm almost sure that this is a bug. > @@ -851,6 +857,7 @@ static int vhdx_log_write(BlockDriverState *bs, BDRVVHDXState *s, > uint32_t partial_sectors = 0; > uint32_t bytes_written = 0; > uint64_t file_offset; > + int64_t file_length; > VHDXHeader *header; > VHDXLogEntryHeader new_hdr; > VHDXLogDescriptor *new_desc = NULL; > @@ -913,10 +920,15 @@ static int vhdx_log_write(BlockDriverState *bs, BDRVVHDXState *s, > .sequence_number = s->log.sequence, > .descriptor_count = sectors, > .reserved = 0, > - .flushed_file_offset = bdrv_getlength(bs->file->bs), > - .last_file_offset = bdrv_getlength(bs->file->bs), > }; > > + file_length = bdrv_getlength(bs->file->bs); > + if (file_length < 0) { > + ret = file_length; > + goto exit; > + } > + new_hdr.flushed_file_offset = file_length; > + new_hdr.last_file_offset = file_length; > new_hdr.log_guid = header->log_guid; If you move the bdrv_getlength() above the initialisation of new_hdr, you could keep these fields in the designated initialiser, which should be better for readability. I also don't know why .log_guid isn't part if it, could be moved, too. > desc_sectors = vhdx_compute_desc_sectors(new_hdr.descriptor_count); > diff --git a/block/vhdx.c b/block/vhdx.c > index a9cecd2..6a14999 100644 > --- a/block/vhdx.c > +++ b/block/vhdx.c > @@ -1166,7 +1166,14 @@ exit: > static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s, > uint64_t *new_offset) > { > - *new_offset = bdrv_getlength(bs->file->bs); > + int64_t current_len; > + current_len = bdrv_getlength(bs->file->bs); > + > + if (current_len < 0) { > + return current_len; > + } Don't you want the empty line to be between declaration and code rather than assignment and check? > + *new_offset = current_len; > > /* per the spec, the address for a block is in units of 1MB */ > *new_offset = ROUND_UP(*new_offset, 1024 * 1024); So the code looks correct, but we could make it a little nicer in a v2. Kevin