[PATCH 1/4] vu_common: Tighten vu_packet_check_range()

[David Gibson <david@gibson.dropbear.id.au>]

This function verifies that the given packet is within the mmap()ed memory
region of the vhost-user device.  We can do better, however.  The packet
should be not only within the mmap()ed range, but specifically in the
subsection of that range set aside for shared buffers, which starts at
dev_region->mmap_offset within there.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 vu_common.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/vu_common.c b/vu_common.c
index 686a09b2..9eea4f2f 100644
--- a/vu_common.c
+++ b/vu_common.c
@@ -37,10 +37,10 @@ int vu_packet_check_range(void *buf, const char *ptr, size_t len)
 
 	for (dev_region = buf; dev_region->mmap_addr; dev_region++) {
 		/* NOLINTNEXTLINE(performance-no-int-to-ptr) */
-		char *m = (char *)(uintptr_t)dev_region->mmap_addr;
+		char *m = (char *)(uintptr_t)dev_region->mmap_addr +
+			dev_region->mmap_offset;
 
-		if (m <= ptr &&
-		    ptr + len <= m + dev_region->mmap_offset + dev_region->size)
+		if (m <= ptr && ptr + len <= m + dev_region->size)
 			return 0;
 	}
 
-- 
@@ -37,10 +37,10 @@ int vu_packet_check_range(void *buf, const char *ptr, size_t len)
 
 	for (dev_region = buf; dev_region->mmap_addr; dev_region++) {
 		/* NOLINTNEXTLINE(performance-no-int-to-ptr) */
-		char *m = (char *)(uintptr_t)dev_region->mmap_addr;
+		char *m = (char *)(uintptr_t)dev_region->mmap_addr +
+			dev_region->mmap_offset;
 
-		if (m <= ptr &&
-		    ptr + len <= m + dev_region->mmap_offset + dev_region->size)
+		if (m <= ptr && ptr + len <= m + dev_region->size)
 			return 0;
 	}
 
-- 
2.48.1