[Qemu-devel] [PATCH v2 2.1 4/4] ide: Treat read/write beyond end as invalid

[Markus Armbruster]

The block layer fails such reads and writes just fine.  However, they
then get treated like valid operations that fail: the error action
gets executed.  Unwanted; reporting the error to the guest is the only
sensible action.

Reject them before passing them to the block layer.  This bypasses the
error action and, for PIO but not DMA, I/O accounting.  Tolerable,
because I/O accounting is an inconsistent mess anyway.

Signed-off-by: Markus Armbruster <address@hidden>
---
 hw/ide/core.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 3a38f1e..63a500d 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -499,6 +499,18 @@ static void ide_rw_error(IDEState *s) {
     ide_set_irq(s->bus);
 }
 
+static bool ide_sect_range_ok(IDEState *s,
+                              uint64_t sector, uint64_t nb_sectors)
+{
+    uint64_t total_sectors;
+
+    bdrv_get_geometry(s->bs, &total_sectors);
+    if (sector > total_sectors || nb_sectors > total_sectors - sector) {
+        return false;
+    }
+    return true;
+}
+
 static void ide_sector_read_cb(void *opaque, int ret)
 {
     IDEState *s = opaque;
@@ -554,6 +566,11 @@ void ide_sector_read(IDEState *s)
     printf("sector=%" PRId64 "\n", sector_num);
 #endif
 
+    if (!ide_sect_range_ok(s, sector_num, n)) {
+        ide_rw_error(s);
+        return;
+    }
+
     s->iov.iov_base = s->io_buffer;
     s->iov.iov_len  = n * BDRV_SECTOR_SIZE;
     qemu_iovec_init_external(&s->qiov, &s->iov, 1);
@@ -671,6 +688,12 @@ void ide_dma_cb(void *opaque, int ret)
            sector_num, n, s->dma_cmd);
 #endif
 
+    if (!ide_sect_range_ok(s, sector_num, n)) {
+        dma_buf_commit(s);
+        ide_dma_error(s);
+        goto eot;
+    }
+
     switch (s->dma_cmd) {
     case IDE_DMA_READ:
         s->bus->dma->aiocb = dma_bdrv_read(s->bs, &s->sg, sector_num,
@@ -790,6 +813,11 @@ void ide_sector_write(IDEState *s)
         n = s->req_nb_sectors;
     }
 
+    if (!ide_sect_range_ok(s, sector_num, n)) {
+        ide_rw_error(s);
+        return;
+    }
+
     s->iov.iov_base = s->io_buffer;
     s->iov.iov_len  = n * BDRV_SECTOR_SIZE;
     qemu_iovec_init_external(&s->qiov, &s->iov, 1);
-- 
1.9.3