[PATCH v12-S2 01/11] net/dpaa2: fix integer overflow in CCSR region mapping

[Prashant Gupta]

From: Hemant Agrawal <hemant.agrawal at nxp.com>

In lsx_ccsr_map_region, PAGE_SIZE is a macro defined as
sysconf(_SC_PAGESIZE), which returns a signed long and may be negative
on error. The value was used directly in size_t comparisons and passed
to mmap, causing an integer overflow (Coverity CID 49765682).

The old round-down "len & PAGE_MASK" ignored the in-page offset: for a
4096-byte or 6656-byte len on a 64K-page kernel the masked result is 0,
causing the mapping to fail, where the old code would have bumped len up
to PAGE_SIZE. The correct mapping size must cover the region from the
page-aligned start through offset + len.

Fix by calling sysconf(_SC_PAGESIZE) explicitly into a signed long,
checking for a non-positive return before use, computing page_mask from
the verified value, and using RTE_ALIGN_CEIL(offset + len, page_size)
for map_len so that the mmap covers the full requested region regardless
of page size. The page-aligned start address and the back-pointer offset
are both derived from the same page_mask, keeping the three values
consistent.

Coverity issue: 49765682
Fixes: f023d059769f ("net/dpaa2: support recycle loopback port")
Cc: stable at dpdk.org
Signed-off-by: Hemant Agrawal <hemant.agrawal at nxp.com>
---
 drivers/net/dpaa2/dpaa2_recycle.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/net/dpaa2/dpaa2_recycle.c b/drivers/net/dpaa2/dpaa2_recycle.c
index f78d12362e..9b6ae3f515 100644
--- a/drivers/net/dpaa2/dpaa2_recycle.c
+++ b/drivers/net/dpaa2/dpaa2_recycle.c
@@ -176,6 +176,9 @@ static void *lsx_ccsr_map_region(uint64_t addr, size_t len)
 	void *tmp;
 	uint64_t start;
 	uint64_t offset;
+	uint64_t page_mask;
+	long page_size;
+	size_t map_len;
 
 	fd = open("/dev/mem", O_RDWR);
 	if (fd < 0) {
@@ -183,20 +186,24 @@ static void *lsx_ccsr_map_region(uint64_t addr, size_t len)
 		return NULL;
 	}
 
-	start = addr & PAGE_MASK;
+	page_size = sysconf(_SC_PAGESIZE);
+	if (page_size <= 0) {
+		close(fd);
+		return NULL;
+	}
+	page_mask = ~((uint64_t)page_size - 1);
+	start = addr & page_mask;
 	offset = addr - start;
-	len = len & PAGE_MASK;
-	if (len < (size_t)PAGE_SIZE)
-		len = PAGE_SIZE;
+	map_len = RTE_ALIGN_CEIL(offset + len, (size_t)page_size);
 
-	tmp = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, start);
+	tmp = mmap(NULL, map_len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, start);
 
 	close(fd);
 
-	if (tmp != MAP_FAILED)
-		return (uint8_t *)tmp + offset;
-	else
+	if (tmp == MAP_FAILED)
 		return NULL;
+
+	return (uint8_t *)tmp + offset;
 }
 
 static const uint8_t ls_sd1_prot_idx_map[] = {
-- 
2.43.0