[Stable-11.0.4 092/120] block/cloop: fix integer overflow in total_sectors calculation

From: malike <[email protected]>

The total_sectors is computed as n_blocks * sectors_per_block where
both operands are uint32_t. The multiplication is performed in 32-bit
arithmetic and can overflow when the product exceeds UINT32_MAX,
producing a value much smaller than the true image size. The result
is assigned to int64_t total_sectors but the 32-bit multiplication
has already wrapped around, and the zero-extension to 64-bit does
not recover the correct value.

This causes the block layer to reject valid I/O requests (DoS) when
the reported total_sectors is smaller than the actual image.

Use 64-bit arithmetic by casting one operand to uint64_t so the
multiplication is performed in 64-bit precision.

Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3972
Signed-off-by: Ma Like <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>
(cherry picked from commit 0d3db94a886610c5923e52cc23f841ccb9cb546c)
Signed-off-by: Michael Tokarev <[email protected]>

diff --git a/block/cloop.c b/block/cloop.c
index 443af1444e8..a16f08e6ef6 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -202,7 +202,8 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
     s->current_block = s->n_blocks;
 
     s->sectors_per_block = s->block_size/512;
-    bs->total_sectors = s->n_blocks * s->sectors_per_block;
+    /* Cast to uint64_t to prevent uint32_t overflow */
+    bs->total_sectors = (uint64_t)s->n_blocks * s->sectors_per_block;
     qemu_co_mutex_init(&s->lock);
     return 0;
 
-- 
2.47.3