Edward O'Callaghan has uploaded this change for review.

View Change

realtek_mst_i2c_spi.c: Don't depend on int overflows

Be explicit to mask the first byte after the shifts as
highlighted by Angel Pos.

BUG=none
BRANCH=none
TEST=builds

Change-Id: I7d1215678094d709e79b8f8c96aa3810586cd72e
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Spotted-by: Angel Pons <th3fanbus@gmail.com>
---
M realtek_mst_i2c_spi.c
1 file changed, 6 insertions(+), 6 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/74/48974/1

diff --git a/realtek_mst_i2c_spi.c b/realtek_mst_i2c_spi.c
index dabec70..3e84b23 100644
--- a/realtek_mst_i2c_spi.c
+++ b/realtek_mst_i2c_spi.c
@@ -330,9 +330,9 @@
 	start--;
 	ret |= realtek_mst_i2c_spi_write_register(fd, 0x60, 0x46); // **
 	ret |= realtek_mst_i2c_spi_write_register(fd, 0x61, OPCODE_READ);
-	uint8_t block_idx = start >> 16;
-	uint8_t page_idx  = start >>  8;
-	uint8_t byte_idx  = start;
+	uint8_t block_idx = (start >> 16) & 0xff;
+	uint8_t page_idx  = (start >>  8) & 0xff;
+	uint8_t byte_idx  =  start & 0xff;
 	ret |= realtek_mst_i2c_spi_map_page(fd, block_idx, page_idx, byte_idx);
 	ret |= realtek_mst_i2c_spi_write_register(fd, 0x6a, 0x03);
 	ret |= realtek_mst_i2c_spi_write_register(fd, 0x60, 0x47); // **
@@ -384,9 +384,9 @@
 		uint16_t page_len = min(len - i, PAGE_SIZE);
 		if (len - i < PAGE_SIZE)
 			ret |= realtek_mst_i2c_spi_write_register(fd, 0x71, page_len-1);
-		uint8_t block_idx = (start + i) >> 16;
-		uint8_t page_idx  = (start + i) >>  8;
-		uint8_t byte_idx = start + i;
+		uint8_t block_idx = ((start + i) >> 16) & 0xff;
+		uint8_t page_idx  = ((start + i) >>  8) & 0xff;
+		uint8_t byte_idx  =  (start + i) & 0xff;
 		ret |= realtek_mst_i2c_spi_map_page(fd, block_idx, page_idx, byte_idx);
 		if (ret)
 			break;

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