From: David Gibson <david@gibson.dropbear.id.au>
To: passt-dev@passt.top, Stefano Brivio <sbrivio@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Subject: [PATCH v2 05/11] packet: Correct type of PACKET_MAX_LEN
Date: Mon, 17 Mar 2025 20:24:18 +1100 [thread overview]
Message-ID: <20250317092424.1461719-6-david@gibson.dropbear.id.au> (raw)
In-Reply-To: <20250317092424.1461719-1-david@gibson.dropbear.id.au>
PACKET_MAX_LEN is usually involved in calculations on size_t values - the
type of the iov_len field in struct iovec. However, being defined bare as
UINT16_MAX, the compiled is likely to assign it a shorter type. This can
lead to unexpected promotions (or lack thereof). Add a cast to force the
type to be what we expect.
Fixes: c43972ad6 ("packet: Give explicit name to maximum packet size")
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
packet.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/packet.h b/packet.h
index dd18461b..9061dad7 100644
--- a/packet.h
+++ b/packet.h
@@ -9,7 +9,7 @@
#include <stdbool.h>
/* Maximum size of a single packet stored in pool, including headers */
-#define PACKET_MAX_LEN UINT16_MAX
+#define PACKET_MAX_LEN ((size_t)UINT16_MAX)
/**
* struct pool - Generic pool of packets stored in a buffer
--
@@ -9,7 +9,7 @@
#include <stdbool.h>
/* Maximum size of a single packet stored in pool, including headers */
-#define PACKET_MAX_LEN UINT16_MAX
+#define PACKET_MAX_LEN ((size_t)UINT16_MAX)
/**
* struct pool - Generic pool of packets stored in a buffer
--
2.48.1
next prev parent reply other threads:[~2025-03-17 10:02 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-17 9:24 [PATCH v2 00/11] Improve robustness of calculations related to frame size limits David Gibson
2025-03-17 9:24 ` [PATCH v2 01/11] vu_common: Tighten vu_packet_check_range() David Gibson
2025-03-17 9:24 ` [PATCH v2 02/11] packet: More cautious checks to avoid pointer arithmetic UB David Gibson
2025-03-17 9:24 ` [PATCH v2 03/11] tap: Make size of pool_tap[46] purely a tuning parameter David Gibson
2025-03-17 9:24 ` [PATCH v2 04/11] tap: Clarify calculation of TAP_MSGS David Gibson
2025-03-17 9:24 ` David Gibson [this message]
2025-03-17 9:24 ` [PATCH v2 06/11] packet: Avoid integer overflows in packet_get_do() David Gibson
2025-03-17 9:24 ` [PATCH v2 07/11] packet: Move checks against PACKET_MAX_LEN to packet_check_range() David Gibson
2025-03-17 9:24 ` [PATCH v2 08/11] packet: Rework packet_get() versus packet_get_try() David Gibson
2025-03-17 9:24 ` [PATCH v2 09/11] util: Add abort_with_msg() and ASSERT_WITH_MSG() helpers David Gibson
2025-03-17 9:24 ` [PATCH v2 10/11] packet: ASSERT on signs of pool corruption David Gibson
2025-03-17 9:24 ` [PATCH v2 11/11] packet: Upgrade severity of most packet errors David Gibson
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