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[Qemu-block] [PULL v2 02/16] block: fix permission update in bdrv_replac

From: Max Reitz
Subject: [Qemu-block] [PULL v2 02/16] block: fix permission update in bdrv_replace_node
Date: Tue, 3 Sep 2019 15:35:39 +0200

From: Vladimir Sementsov-Ogievskiy <address@hidden>

It's wrong to OR shared permissions. It may lead to crash on further
permission updates.
Also, no needs to consider previously calculated permissions, as at
this point we already bind all new parents and bdrv_get_cumulative_perm
result is enough. So fix the bug by just set permissions by
bdrv_get_cumulative_perm result.

Bug was introduced in long ago 234ac1a9025, in 2.9.

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
Message-id: address@hidden
Signed-off-by: Max Reitz <address@hidden>
 block.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/block.c b/block.c
index 874a29a983..5944124845 100644
--- a/block.c
+++ b/block.c
@@ -4165,7 +4165,6 @@ void bdrv_replace_node(BlockDriverState *from, 
BlockDriverState *to,
     BdrvChild *c, *next;
     GSList *list = NULL, *p;
-    uint64_t old_perm, old_shared;
     uint64_t perm = 0, shared = BLK_PERM_ALL;
     int ret;
@@ -4211,8 +4210,8 @@ void bdrv_replace_node(BlockDriverState *from, 
BlockDriverState *to,
-    bdrv_get_cumulative_perm(to, &old_perm, &old_shared);
-    bdrv_set_perm(to, old_perm | perm, old_shared | shared);
+    bdrv_get_cumulative_perm(to, &perm, &shared);
+    bdrv_set_perm(to, perm, shared);

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