fix(virtqueue): next_off must not be shifted

Signed-off-by: Martin Kröning <martin.kroening@eonerc.rwth-aachen.de>
hermit-os · May 30, 2024 · 83f3ca3 · 83f3ca3
1 parent b911737
commit 83f3ca3
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Showing 2 changed files with 4 additions and 8 deletions.
diff --git a/src/drivers/virtio/virtqueue/packed.rs b/src/drivers/virtio/virtqueue/packed.rs
@@ -971,8 +971,7 @@ impl Virtq for PackedVq {
 		if self.dev_event.is_notif() | self.dev_event.is_notif_specfic(next_off, next_wrap) {
 			let index = self.index.0.to_le_bytes();
 			let mut index = index.iter();
-			// Even on 64bit systems this is fine, as we have a queue_size < 2^15!
-			let det_notif_data: u16 = (next_off as u16) >> 1;
+			let det_notif_data: u16 = (next_off as u16) & !(1 << 15);
 			let flags = (det_notif_data | (u16::from(next_wrap) << 15)).to_le_bytes();
 			let mut flags = flags.iter();
 			let mut notif_data: [u8; 4] = [0, 0, 0, 0];
@@ -1014,8 +1013,7 @@ impl Virtq for PackedVq {
 		if self.dev_event.is_notif() {
 			let index = self.index.0.to_le_bytes();
 			let mut index = index.iter();
-			// Even on 64bit systems this is fine, as we have a queue_size < 2^15!
-			let det_notif_data: u16 = (next_off as u16) >> 1;
+			let det_notif_data: u16 = (next_off as u16) & !(1 << 15);
 			let flags = (det_notif_data | (u16::from(next_wrap) << 15)).to_le_bytes();
 			let mut flags = flags.iter();
 			let mut notif_data: [u8; 4] = [0, 0, 0, 0];
@@ -1044,8 +1042,7 @@ impl Virtq for PackedVq {
 		if self.dev_event.is_notif() {
 			let index = self.index.0.to_le_bytes();
 			let mut index = index.iter();
-			// Even on 64bit systems this is fine, as we have a queue_size < 2^15!
-			let det_notif_data: u16 = (next_off as u16) >> 1;
+			let det_notif_data: u16 = (next_off as u16) & !(1 << 15);
 			let flags = (det_notif_data | (u16::from(next_wrap) << 15)).to_le_bytes();
 			let mut flags = flags.iter();
 			let mut notif_data: [u8; 4] = [0, 0, 0, 0];

diff --git a/src/drivers/virtio/virtqueue/split.rs b/src/drivers/virtio/virtqueue/split.rs
@@ -380,8 +380,7 @@ impl Virtq for SplitVq {
 		if self.ring.borrow().dev_is_notif() {
 			let index = self.index.0.to_le_bytes();
 			let mut index = index.iter();
-			// Even on 64bit systems this is fine, as we have a queue_size < 2^15!
-			let det_notif_data: u16 = next_off >> 1;
+			let det_notif_data: u16 = next_off & !(1 << 15);
 			let flags = (det_notif_data | (next_wrap << 15)).to_le_bytes();
 			let mut flags = flags.iter();
 			let mut notif_data: [u8; 4] = [0, 0, 0, 0];