Attachment 711848 Details for Bug 922671 – Proposed patch - part 3 - Take alignment in acount for free_bytes in ring buffer

[patch] Proposed patch - part 3 - Take alignment in acount for free_bytes in ring buffer

2013-03-07-0001-coroipcs-Ensure-rb-data-are-not-overwritten.patch (text/plain), 1.15 KB, created by Jan Friesse on 2013-03-18 10:03:47 UTC

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Creator: Jan Friesse

Created: 2013-03-18 10:03:47 UTC

Size: 1.15 KB

patch

obsolete

>From 6d474fb9bf9cc396c02dd6fe08a6e858ce2e2d0d Mon Sep 17 00:00:00 2001
>From: Jan Friesse <jfriesse@redhat.com>
>Date: Thu, 7 Mar 2013 17:51:32 +0100
>Subject: [PATCH] coroipcs: Ensure rb data are not overwritten
>
>With introduce of rb alignment (55600762), it's not enough to subtract
>one from number of free bytes, but also alignment must be taken to
>account. Easiest solution is to subtract 9 bytes.
>
>Signed-off-by: Jan Friesse <jfriesse@redhat.com>
>---
> exec/coroipcs.c |   12 ++++++++++--
> 1 files changed, 10 insertions(+), 2 deletions(-)
>
>diff --git a/exec/coroipcs.c b/exec/coroipcs.c
>index 1adb7ae..36d18a4 100644
>--- a/exec/coroipcs.c
>+++ b/exec/coroipcs.c
>@@ -1225,8 +1225,16 @@ static int shared_mem_dispatch_bytes_left (const struct conn_info *conn_info)
> 	} else {
> 		bytes_left = n_read - n_write;
> 	}
>-	if (bytes_left > 0) {
>-		bytes_left--;
>+
>+	/*
>+	 * Pointers in ring buffer are 64-bit alignment (in memcpy_dwrap)
>+	 * To ensure we will not overwrite previous data,
>+	 * 9 bytes (64-bit + 1 byte) are subtracted from bytes_left
>+	 */
>+	if (bytes_left < 9) {
>+		bytes_left = 0;
>+	} else {
>+		bytes_left = bytes_left - 9;
> 	}
> 
> 	return (bytes_left);
>-- 
>1.7.1
>

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