[coreboot-gerrit] Change in coreboot[master]: spi/flashconsole: Fix internal buffer overflow

[Nico Huber (Code Review)]

Hello Paul Menzel, Michael Niewöhner,

I'd like you to do a code review. Please visit

https://review.coreboot.org/c/coreboot/+/48074

to review the following change.

Change subject: spi/flashconsole: Fix internal buffer overflow
......................................................................

spi/flashconsole: Fix internal buffer overflow

Once the console's FMAP region is full, we stop clearing the line
buffer and `line_offset` is not reset anymore. Hence, sanity check
`line_offset` everytime before writing to the buffer.

Change-Id: I36e9037d7baf8c1ed8b2d0c120bfffa58c089c95
Signed-off-by: Nico Huber 
---
M src/drivers/spi/flashconsole.c
1 file changed, 2 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/74/48074/1

diff --git a/src/drivers/spi/flashconsole.c b/src/drivers/spi/flashconsole.c
index 654177f..d5c4382 100644
--- a/src/drivers/spi/flashconsole.c
+++ b/src/drivers/spi/flashconsole.c
@@ -75,7 +75,8 @@

size_t region_size = region_device_sz(rdev_ptr);

-	line_buffer[line_offset++] = c;
+	if (line_offset < LINE_BUFFER_SIZE)
+		line_buffer[line_offset++] = c;

if (line_offset >= LINE_BUFFER_SIZE ||
        offset + line_offset >= region_size || c == '\n') {