linux-kernel - [RFC PATCH 2/7] rslib: Fix decoding of shortened codes

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Message-Id: <20190330182947.8823-3-ferdinand.blomqvist@gmail.com>
Date:   Sat, 30 Mar 2019 20:29:42 +0200
From:   Ferdinand Blomqvist <ferdinand.blomqvist@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>
Subject: [RFC PATCH 2/7] rslib: Fix decoding of shortened codes

The decoder is broken. It only works with full length codes.

Signed-off-by: Ferdinand Blomqvist <ferdinand.blomqvist@...il.com>
---
 lib/reed_solomon/decode_rs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/reed_solomon/decode_rs.c b/lib/reed_solomon/decode_rs.c
index 1db74eb098d0..3313bf944ff1 100644
--- a/lib/reed_solomon/decode_rs.c
+++ b/lib/reed_solomon/decode_rs.c
@@ -99,9 +99,9 @@
 	if (no_eras > 0) {
 		/* Init lambda to be the erasure locator polynomial */
 		lambda[1] = alpha_to[rs_modnn(rs,
-					      prim * (nn - 1 - eras_pos[0]))];
+					prim * (nn - 1 - (eras_pos[0] + pad)))];
 		for (i = 1; i < no_eras; i++) {
-			u = rs_modnn(rs, prim * (nn - 1 - eras_pos[i]));
+			u = rs_modnn(rs, prim * (nn - 1 - (eras_pos[i] + pad)));
 			for (j = i + 1; j > 0; j--) {
 				tmp = index_of[lambda[j - 1]];
 				if (tmp != nn) {
-- 
2.17.2