Am 11.07.2017 um 20:50 hat Manos Pitsidianakis geschrieben: > On Tue, Jul 11, 2017 at 05:16:17PM +0200, Kevin Wolf wrote: > >Am 01.07.2017 um 17:39 hat Manos Pitsidianakis geschrieben: > >>bdrv_open_driver() is called in two places, bdrv_new_open_driver() and > >>bdrv_open_common(). In the latter, failure cleanup in is in its caller, > >>bdrv_open_inherit(), which unrefs the bs->file of the failed driver open if > >>it > >>exists. > >> > >>Let's move the bs->file cleanup to bdrv_open_driver() to take care of all > >>callers and do not set bs->drv to NULL unless the driver's open function > >>failed. When bs is destroyed by removing its last reference, bdrv_close() > >>checks bs->drv to perform the needed cleanups and also call the driver's > >>close > >>function. > >> > >>Signed-off-by: Manos Pitsidianakis <el13...@mail.ntua.gr> > >>--- > >> > >>v2: > >> move bdrv_unref_child(bs, bs->file) to bdrv_open_driver > >> do not set bs->drv to NULL if open succeeds > >> > >> block.c | 21 +++++++++++++-------- > >> 1 file changed, 13 insertions(+), 8 deletions(-) > >> > >>diff --git a/block.c b/block.c > >>index 694396281b..df2a46990c 100644 > >>--- a/block.c > >>+++ b/block.c > >>@@ -1091,6 +1091,7 @@ static int bdrv_open_driver(BlockDriverState *bs, > >>BlockDriver *drv, > >> { > >> Error *local_err = NULL; > >> int ret; > >>+ bool open_failed; > >> > >> bdrv_assign_node_name(bs, node_name, &local_err); > >> if (local_err) { > >>@@ -1111,7 +1112,9 @@ static int bdrv_open_driver(BlockDriverState *bs, > >>BlockDriver *drv, > >> ret = 0; > >> } > >> > >>- if (ret < 0) { > >>+ open_failed = ret < 0; > >>+ > >>+ if (open_failed) { > >> if (local_err) { > >> error_propagate(errp, local_err); > >> } else if (bs->filename[0]) { > >>@@ -1142,10 +1145,15 @@ static int bdrv_open_driver(BlockDriverState *bs, > >>BlockDriver *drv, > >> return 0; > >> > >> free_and_fail: > >>- /* FIXME Close bs first if already opened*/ > >>- g_free(bs->opaque); > >>- bs->opaque = NULL; > >>- bs->drv = NULL; > >>+ if (open_failed) { > >>+ g_free(bs->opaque); > >>+ bs->opaque = NULL; > >>+ bs->drv = NULL; > >>+ } > >>+ if (bs->file != NULL) { > >>+ bdrv_unref_child(bs, bs->file); > >>+ bs->file = NULL; > >>+ } > > > >Is this bdrv_unref_child() safe if we leave bs->drv set? Format drivers > >expect that if an image is opened, it also has a valid bs->file. > > > >For example, if I add ret = -1 after refresh_total_sectors() (because I > >couldn't find an easier way to make it fail intentionally), I get an > >ugly heap corruption crash instead of a nice error message with this > >patch. > > > This is triggered by bdrv_open_inherit doing > QDECREF(bs->explicit_options) and leaving the dangling pointer. Not > setting bs->drv means bdrv_close was called and tried to decref it > again, causing the heap error. Setting bs->explicit_options = NULL; > right below that fixes the heap corruption for me.
Wouldn't it be better to call drv->bdrv_close() instead and then set bs->drv/opaque = NULL like for the other error path? > I can send a seperate fix for this. No, this doesn't fail before this patch, so it's a regression and we can't merge the patch without a fix. You need to respin this one. > I also saw that there's no reason to use a boolean, a label would do > just fine so I can change that and finalize the patch in the next > version if everything is okay with it. Yes, that sounds better. Kevin
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