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| author | Dylan Reid <dgreid@chromium.org> | 2019-06-28 15:19:43 +1000 |
|---|---|---|
| committer | Commit Bot <commit-bot@chromium.org> | 2019-07-09 17:46:17 +0000 |
| commit | eecbccc4d9d70b2fd63681a2b3ced6a6aafe81bb (patch) | |
| tree | 7f71cbb71c30490e93a95ee6ab7c5fb9b4118ade | |
| parent | bb5a4f1843361518412d5cd4036e31fb65f36e33 (diff) | |
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qcow: Avoid overflow when taking ceiling of division
The extra % operation will be slower, but none of these divisions are in hot paths. They are only used during setup. Many of these operations take untrusted input from the disk file, so need to be hardened. BUG=979458 TEST=unit tests still pass Signed-off-by: Dylan Reid <dgreid@chromium.org> Change-Id: I0e93c73b345faf643da53ea41bde3349d756bdc7 Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1679891 Reviewed-by: Daniel Verkamp <dverkamp@chromium.org> Tested-by: kokoro <noreply+kokoro@google.com>
| -rw-r--r-- | qcow/src/qcow.rs | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/qcow/src/qcow.rs b/qcow/src/qcow.rs index 7528773..ceaf130 100644 --- a/qcow/src/qcow.rs +++ b/qcow/src/qcow.rs @@ -1554,12 +1554,12 @@ fn offset_is_cluster_boundary(offset: u64, cluster_bits: u32) -> Result<()> { // Ceiling of the division of `dividend`/`divisor`. fn div_round_up_u64(dividend: u64, divisor: u64) -> u64 { - (dividend + divisor - 1) / divisor + dividend / divisor + if dividend % divisor != 0 { 1 } else { 0 } } // Ceiling of the division of `dividend`/`divisor`. fn div_round_up_u32(dividend: u32, divisor: u32) -> u32 { - (dividend + divisor - 1) / divisor + dividend / divisor + if dividend % divisor != 0 { 1 } else { 0 } } fn convert_copy<R, W>(reader: &mut R, writer: &mut W, offset: u64, size: u64) -> Result<()> |