From: Eric Blake <eblake@redhat.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: [Qemu-devel] [PATCH 23/25] fdc: Move floppy geometry guessing back from block.c
Date: Mon, 09 Jul 2012 10:46:48 -0600 [thread overview]
Message-ID: <4FFB0AF8.30906@redhat.com> (raw)
In-Reply-To: <m3sjd0j4tu.fsf@blackfin.pond.sub.org>
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On 07/09/2012 10:07 AM, Markus Armbruster wrote:
>>> This is an unconditional use of fd_type[0]. If floppy == NULL, this is
>>> dereferencing an uninitialized value.
>>>
>>> I'm not sure why the explicit initialization was removed...
>
> Brain fart on my part, sorry. The old loop assigns only if the drive
> exists. The new loop assigns unconditionally. Except the whole loop is
> still conditional.
>
> Testing can't flag this, because floppy is never null.
>
>> Looks broken indeed. I just wonder why my gcc (or the buildbots) didn't
>> complain.
>
> Me too. Looks like I should upgrade to a more recent gcc.
It's probably not the version of the gcc you used, but whether or not
your CFLAGS include -O2. Gcc has the (IMO very annoying) limitation
that uninitialized-use analysis can only be performed if you are also
doing optimization. You have to use a tool like clang or Coverity if
you want more reliable uninitialized-use analysis even while building
-O0 debug images.
--
Eric Blake eblake@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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next prev parent reply other threads:[~2012-07-09 16:46 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-09 14:16 [Qemu-devel] [PULL 00/25] Block patches Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 01/25] qcow2: fix #ifdef'd qcow2_check_refcounts() callers Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 02/25] qcow2: preserve free_byte_offset when qcow2_alloc_bytes() fails Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 03/25] blockdev: warn when copy_on_read=on and readonly=on Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 04/25] sheepdog: fix dprintf format strings Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 05/25] sheepdog: restart I/O when socket becomes ready in do_co_req() Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 06/25] sheepdog: use coroutine based socket functions in coroutine context Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 07/25] sheepdog: make sure we don't free aiocb before sending all requests Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 08/25] sheepdog: split outstanding list into inflight and pending Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 09/25] sheepdog: traverse pending_list from the first for each time Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 10/25] blkdebug: remove sync i/o events Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 11/25] blkdebug: tiny cleanup Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 12/25] blkdebug: pass getlength to underlying file Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 13/25] blkdebug: store list of active rules Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 14/25] blkdebug: optionally tie errors to a specific sector Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 15/25] raw: hook into blkdebug Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 16/25] block: copy over job and dirty bitmap fields in bdrv_append Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 17/25] block: introduce bdrv_swap, implement bdrv_append on top of it Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 18/25] fdc: rewrite seek and DSKCHG bit handling Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 19/25] fdc: fix interrupt handling Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 20/25] fdc_test: update media_change test Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 21/25] fdc_test: introduce test_sense_interrupt Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 22/25] fdc: Drop broken code for user-defined floppy geometry Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 23/25] fdc: Move floppy geometry guessing back from block.c Kevin Wolf
2012-07-09 15:01 ` Anthony Liguori
2012-07-09 15:24 ` Kevin Wolf
2012-07-09 15:45 ` Anthony Liguori
2012-07-09 16:07 ` Markus Armbruster
2012-07-09 16:46 ` Eric Blake [this message]
2012-07-09 17:01 ` Anthony Liguori
2012-07-10 7:41 ` Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 24/25] qtest: Tidy up temporary files properly Kevin Wolf
2012-07-09 14:16 ` [Qemu-devel] [PATCH 25/25] block: Factor bdrv_read_unthrottled() out of guess_disk_lchs() Kevin Wolf
2012-07-09 16:49 ` [Qemu-devel] [PULL 00/25] Block patches Anthony Liguori
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