From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37602) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XgTe9-0002BD-2c for qemu-devel@nongnu.org; Tue, 21 Oct 2014 03:14:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XgTe2-0002ga-J8 for qemu-devel@nongnu.org; Tue, 21 Oct 2014 03:14:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44850) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XgTe2-0002gV-Bn for qemu-devel@nongnu.org; Tue, 21 Oct 2014 03:14:14 -0400 Message-ID: <544607BA.2010206@redhat.com> Date: Tue, 21 Oct 2014 09:14:02 +0200 From: Max Reitz MIME-Version: 1.0 References: <1413815733-22829-1-git-send-email-mreitz@redhat.com> <1413815733-22829-7-git-send-email-mreitz@redhat.com> <20141020164420.GT3585@noname.redhat.com> In-Reply-To: <20141020164420.GT3585@noname.redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v6 06/11] qcow2: Fix refcount blocks beyond image end List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, Stefan Hajnoczi , =?windows-1252?Q?Beno=EEt_Canet?= On 2014-10-20 at 18:44, Kevin Wolf wrote: > Am 20.10.2014 um 16:35 hat Max Reitz geschrieben: >> If the qcow2 check function detects a refcount block located beyond the >> image end, grow the image appropriately. This cannot break anything and >> is the logical fix for such a case. >> >> Signed-off-by: Max Reitz >> Reviewed-by: Eric Blake >> --- >> block/qcow2-refcount.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++---- >> 1 file changed, 58 insertions(+), 4 deletions(-) >> >> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c >> index 55a539f..0225769 100644 >> --- a/block/qcow2-refcount.c >> +++ b/block/qcow2-refcount.c >> @@ -1544,7 +1544,8 @@ static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res, >> int64_t *nb_clusters) >> { >> BDRVQcowState *s = bs->opaque; >> - int64_t i; >> + int64_t i, size; >> + int ret; >> >> for(i = 0; i < s->refcount_table_size; i++) { >> uint64_t offset, cluster; >> @@ -1560,9 +1561,62 @@ static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res, >> } >> >> if (cluster >= *nb_clusters) { >> - fprintf(stderr, "ERROR refcount block %" PRId64 >> - " is outside image\n", i); >> - res->corruptions++; >> + fprintf(stderr, "%s refcount block %" PRId64 " is outside image\n", >> + fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR", i); >> + >> + if (fix & BDRV_FIX_ERRORS) { >> + int64_t old_nb_clusters = *nb_clusters; >> + >> + if (offset + s->cluster_size < offset || >> + offset + s->cluster_size > INT64_MAX) > I _think_ this code is correct because offset is unsigned, but it would > be easier and not rely on overflow semantics like this: > > if (offset > INT64_MAX - s->cluster_size) Okay. >> + { >> + ret = -EINVAL; >> + goto resize_fail; >> + } >> + >> + ret = bdrv_truncate(bs->file, offset + s->cluster_size); >> + if (ret < 0) { >> + goto resize_fail; >> + } >> + size = bdrv_getlength(bs->file); >> + if (size < 0) { >> + ret = size; >> + goto resize_fail; >> + } >> + >> + *nb_clusters = size_to_clusters(s, size); >> + assert(*nb_clusters >= old_nb_clusters); >> + >> + *refcount_table = g_try_realloc(*refcount_table, >> + *nb_clusters * sizeof(uint16_t)); >> + if (!*refcount_table) { >> + res->check_errors++; >> + return -ENOMEM; >> + } >> + >> + memset(*refcount_table + old_nb_clusters, 0, >> + (*nb_clusters - old_nb_clusters) * sizeof(uint16_t)); > Considering the comments you got in previous comments, > sizeof(**refcount_table) might make it more obvious what's going on, and > would also be more robust against later changes of the type. I highly doubt I'll change the type so that sizeof(**refcount_table) works. If variable refcounts are implemented, I'll probably make *refcount_table just a void * and then access its elements through a function; sadly, qemu's make doesn't error out against sizeof(void) (which would be -Wpointer-arith or just -pedantic), so just using sizeof(**refcount_table) so that everything throws an error once it's a void ** won't work. I guess I'll change it in a v7 because sizeof(**refcount_table) is easier to grep for than sizeof(uint16_t). >> + if (cluster >= *nb_clusters) { >> + ret = -EINVAL; >> + goto resize_fail; >> + } >> + >> + res->corruptions_fixed++; >> + inc_refcounts(bs, res, *refcount_table, *nb_clusters, >> + offset, s->cluster_size); >> + /* No need to check whether the refcount is now greater than 1: >> + * This area was just allocated and zeroed, so it can only be >> + * exactly 1 after inc_refcounts() */ >> + continue; >> + >> +resize_fail: >> + res->corruptions++; >> + fprintf(stderr, "ERROR could not resize image: %s\n", >> + strerror(-ret)); >> + } else { >> + res->corruptions++; >> + } >> continue; >> } > Reviewed-by: Kevin Wolf Thanks! Max