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[RESEND,04/10] via-cuda: Prevent read buffer overflow

Message ID 0f17040d7530acb6f3ebd7b592cca8dfb21d2b64.1483055859.git.fthain@telegraphics.com.au (mailing list archive)
State Accepted
Headers show

Commit Message

Finn Thain Jan. 1, 2017, 12:56 a.m. UTC 
If the Cuda driver does not enter the 'read_done' state for some
reason, it may continue in the 'reading' state until the buffer
overflows. Add a bounds check to prevent this.

Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/macintosh/via-cuda.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/macintosh/via-cuda.c b/drivers/macintosh/via-cuda.c
index 64a04af..1cf1467 100644
--- a/drivers/macintosh/via-cuda.c
+++ b/drivers/macintosh/via-cuda.c
@@ -470,6 +470,8 @@  cuda_poll(void)
 }
 EXPORT_SYMBOL(cuda_poll);
 
+#define ARRAY_FULL(a, p)	((p) - (a) == ARRAY_SIZE(a))
+
 static irqreturn_t
 cuda_interrupt(int irq, void *arg)
 {
@@ -558,7 +560,11 @@  cuda_interrupt(int irq, void *arg)
 	break;
 
     case reading:
-	*reply_ptr++ = in_8(&via[SR]);
+	if (reading_reply ? ARRAY_FULL(current_req->reply, reply_ptr)
+	                  : ARRAY_FULL(cuda_rbuf, reply_ptr))
+	    (void)in_8(&via[SR]);
+	else
+	    *reply_ptr++ = in_8(&via[SR]);
 	if (!TREQ_asserted(status)) {
 	    /* that's all folks */
 	    negate_TIP_and_TACK();