ide: Clear DRQ after handling all expected accesses

This is additional hardening against an end_transfer_func that fails to
clear the DRQ status bit. The bit must be unset as soon as the PIO
transfer has completed, so it's better to do this in a central place
instead of duplicating the code in all commands (and forgetting it in
some).

[ This is XSA-138 / CVE-2015-5154. ]

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/hw/ide.c b/hw/ide.c
index 211ec88588a4488a7d8f9a1de66ce7b08c75ea9a..7b84d1b0e4357b0597409ab2feaaa5b0b2715357 100644 (file)
--- a/hw/ide.c
+++ b/hw/ide.c
@@ -3009,8 +3009,10 @@ static void ide_data_writew(void *opaque, uint32_t addr, uint32_t val)
     *(uint16_t *)p = le16_to_cpu(val);
     p += 2;
     s->data_ptr = p;
-    if (p >= s->data_end)
+    if (p >= s->data_end) {
+        s->status &= ~DRQ_STAT;
         s->end_transfer_func(s);
+    }
 }
 
 static uint32_t ide_data_readw(void *opaque, uint32_t addr)
@@ -3032,8 +3034,10 @@ static uint32_t ide_data_readw(void *opaque, uint32_t addr)
     ret = cpu_to_le16(*(uint16_t *)p);
     p += 2;
     s->data_ptr = p;
-    if (p >= s->data_end)
+    if (p >= s->data_end) {
+        s->status &= ~DRQ_STAT;
         s->end_transfer_func(s);
+    }
     return ret;
 }
 
@@ -3055,8 +3059,10 @@ static void ide_data_writel(void *opaque, uint32_t addr, uint32_t val)
     *(uint32_t *)p = le32_to_cpu(val);
     p += 4;
     s->data_ptr = p;
-    if (p >= s->data_end)
+    if (p >= s->data_end) {
+        s->status &= ~DRQ_STAT;
         s->end_transfer_func(s);
+    }
 }
 
 static uint32_t ide_data_readl(void *opaque, uint32_t addr)
@@ -3078,8 +3084,10 @@ static uint32_t ide_data_readl(void *opaque, uint32_t addr)
     ret = cpu_to_le32(*(uint32_t *)p);
     p += 4;
     s->data_ptr = p;
-    if (p >= s->data_end)
+    if (p >= s->data_end) {
+        s->status &= ~DRQ_STAT;
         s->end_transfer_func(s);
+    }
     return ret;
 }