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[Qemu-devel] [PULL 15/15] block/parallels: Avoid overflows
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PULL 15/15] block/parallels: Avoid overflows |
Date: |
Mon, 3 Apr 2017 17:33:55 +0200 |
Change the types of variables in allocate_clusters() to int64_t so we do
not have to worry about potential overflows.
Add an assertion that our accesses to s->bat[] do not result in a buffer
overflow and that the implicit conversion performed when invoking
bat_entry_off() does not result in an integer overflow.
Coverity-id: 1307776
Signed-off-by: Max Reitz <address@hidden>
Message-id: address@hidden
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
---
block/parallels.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/block/parallels.c b/block/parallels.c
index 4173b3fb9d..90acf79687 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -192,8 +192,7 @@ static int64_t allocate_clusters(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, int *pnum)
{
BDRVParallelsState *s = bs->opaque;
- uint32_t idx, to_allocate, i;
- int64_t pos, space;
+ int64_t pos, space, idx, to_allocate, i;
pos = block_status(s, sector_num, nb_sectors, pnum);
if (pos > 0) {
@@ -201,11 +200,19 @@ static int64_t allocate_clusters(BlockDriverState *bs,
int64_t sector_num,
}
idx = sector_num / s->tracks;
- if (idx >= s->bat_size) {
- return -EINVAL;
- }
-
to_allocate = DIV_ROUND_UP(sector_num + *pnum, s->tracks) - idx;
+
+ /* This function is called only by parallels_co_writev(), which will never
+ * pass a sector_num at or beyond the end of the image (because the block
+ * layer never passes such a sector_num to that function). Therefore, idx
+ * is always below s->bat_size.
+ * block_status() will limit *pnum so that sector_num + *pnum will not
+ * exceed the image end. Therefore, idx + to_allocate cannot exceed
+ * s->bat_size.
+ * Note that s->bat_size is an unsigned int, therefore idx + to_allocate
+ * will always fit into a uint32_t. */
+ assert(idx < s->bat_size && idx + to_allocate <= s->bat_size);
+
space = to_allocate * s->tracks;
if (s->data_end + space > bdrv_getlength(bs->file->bs) >>
BDRV_SECTOR_BITS) {
int ret;
--
2.12.1
- [Qemu-devel] [PULL 04/15] io vnc sockets: Clean up SocketAddressKind switches, (continued)
- [Qemu-devel] [PULL 04/15] io vnc sockets: Clean up SocketAddressKind switches, Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 05/15] block: Document -drive problematic code and bugs, Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 06/15] gluster: Prepare for SocketAddressFlat extension, Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 07/15] qapi-schema: SocketAddressFlat variants 'vsock' and 'fd', Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 08/15] sockets: New helper socket_address_crumple(), Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 09/15] nbd: Tidy up blockdev-add interface, Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 11/15] qemu-io-cmds: Assert that global and nofile commands don't use ct->perms, Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 10/15] sheepdog: Fix blockdev-add, Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 13/15] qcow2: Discard unaligned tail when wiping image, Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 12/15] iotests: fix 097 when run with qcow, Max Reitz, 2017/04/03
- [Qemu-devel] [PULL 15/15] block/parallels: Avoid overflows,
Max Reitz <=
- [Qemu-devel] [PULL 14/15] iotests: Improve image-clear tests on non-aligned image, Max Reitz, 2017/04/03
- Re: [Qemu-devel] [PULL 00/15] Block patches for rc3, Peter Maydell, 2017/04/03