From 86fa8da83771238de55dc44819a1a27bafef5353 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 28 May 2010 12:21:27 +0200 Subject: [PATCH] qcow2: Fix corruption after error in update_refcount After it is done with updating refcounts in the cache, update_refcount writes all changed entries to disk. If a refcount block allocation fails, however, there was no change yet and therefore first_index = last_index = -1. Don't treat -1 as a normal sector index (resulting in a 512 byte write!) but return without updating anything in this case. Signed-off-by: Kevin Wolf --- block/qcow2-refcount.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 5b7cda4774..22b0b45ff7 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -417,6 +417,10 @@ static int write_refcount_block_entries(BlockDriverState *bs, return 0; } + if (first_index < 0) { + return 0; + } + first_index &= ~(REFCOUNTS_PER_SECTOR - 1); last_index = (last_index + REFCOUNTS_PER_SECTOR) & ~(REFCOUNTS_PER_SECTOR - 1); -- 2.11.4.GIT