[coreboot-gerrit] Change in coreboot[master]: drivers/spi/spi-generic: fix edge case in spi_crop_chunk

[Felix Held (Code Review)]

Felix Held has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/60121 )

Change subject: drivers/spi/spi-generic: fix edge case in spi_crop_chunk
......................................................................

drivers/spi/spi-generic: fix edge case in spi_crop_chunk

In the case of deduct_cmd_len being set and the adjusted cmd_len >=
ctrlr_max, ctrlr_max wasn't being adjusted and still had the value of
ctrlr->max_xfer_size. Handle this edge case (which we should never run
into) by setting ctrlr_max to 0 and printing a warning to the console.

Signed-off-by: Felix Held 
Change-Id: I9941b2947bb0a44dfae8ee69f509795dfb0cb241
---
M src/drivers/spi/spi-generic.c
1 file changed, 8 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/21/60121/1

diff --git a/src/drivers/spi/spi-generic.c b/src/drivers/spi/spi-generic.c
index 116daf9..9796663 100644
--- a/src/drivers/spi/spi-generic.c
+++ b/src/drivers/spi/spi-generic.c
@@ -98,8 +98,14 @@
    if (deduct_opcode_len)
    	cmd_len--;

-	if (deduct_cmd_len && (ctrlr_max > cmd_len))
-		ctrlr_max -= cmd_len;
+	if (deduct_cmd_len) {
+		if (ctrlr_max >= cmd_len) {
+			ctrlr_max -= cmd_len;
+		} else {
+			ctrlr_max = 0;
+			printk(BIOS_WARNING, "%s: Command longer than buffer\n", __func__);
+		}
+	}

return MIN(ctrlr_max, buf_len);
 }