[PATCH 01/13] platform/x86: hp-bioscfg: fix off-by-one write in hp_get_string_from_buffer

[Muhammad Bilal <meatuni001@gmail.com>]

hp_get_string_from_buffer() clamps the converted string length against
the destination buffer size with "size > dst_size", so when the
converted length is exactly equal to dst_size, conv_dst_size is left
at dst_size and the unconditional NUL terminator write

	dst[conv_dst_size] = 0;

lands one byte past the destination buffer. This is the same shape of
bug as the previously fixed off-by-one in hp_convert_hexstr_to_str():
the buffer is sized correctly for the content, but the terminator
write is never checked against that size.

Fix by changing the comparison to ">=" so conv_dst_size is always left
with room for the terminator.

All fixed-size destinations that reach this function (path[512],
current_value[512], current_password/current_value[64], and the
per-entry buffers in encodings[][512] and prerequisites[][512]) are
affected.

Fixes: a34fc329b189 ("platform/x86: hp-bioscfg: bioscfg")
Cc: stable@vger.kernel.org
Signed-off-by: Muhammad Bilal <meatuni001@gmail.com>
---
 drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
index 2bf57e6eade4..0edc6e7cfa9a 100644
--- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
+++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
@@ -85,7 +85,7 @@ int hp_get_string_from_buffer(u8 **buffer, u32 *buffer_size, char *dst, u32 dst_
 	 * bytes.
 	 */
 	conv_dst_size = size;
-	if (size > dst_size)
+	if (size >= dst_size)
 		conv_dst_size = dst_size - 1;
 
 	/*
-- 
2.55.0