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[Qemu-devel] [PATCH 1/2] qcow2: Do not overflow when writing an L1 secto
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH 1/2] qcow2: Do not overflow when writing an L1 sector |
Date: |
Thu, 16 Oct 2014 15:25:56 +0200 |
While writing an L1 table sector, qcow2_write_l1_entry() copies the
respective range from s->l1_table to the local "buf" array. The size of
s->l1_table does not have to be a multiple of L1_ENTRIES_PER_SECTOR;
thus, limit the index which is used for copying all entries to the L1
size.
Cc: address@hidden
Signed-off-by: Max Reitz <address@hidden>
---
block/qcow2-cluster.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index f7dd8c0..4d888c7 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -164,12 +164,14 @@ static int l2_load(BlockDriverState *bs, uint64_t
l2_offset,
int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index)
{
BDRVQcowState *s = bs->opaque;
- uint64_t buf[L1_ENTRIES_PER_SECTOR];
+ uint64_t buf[L1_ENTRIES_PER_SECTOR] = { 0 };
int l1_start_index;
int i, ret;
l1_start_index = l1_index & ~(L1_ENTRIES_PER_SECTOR - 1);
- for (i = 0; i < L1_ENTRIES_PER_SECTOR; i++) {
+ for (i = 0; i < L1_ENTRIES_PER_SECTOR && l1_start_index + i < s->l1_size;
+ i++)
+ {
buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]);
}
--
2.1.2