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authorFerdinand Blomqvist <ferdinand.blomqvist@gmail.com>2019-06-20 17:10:34 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-08-04 09:34:48 +0200
commita7a7839b5537a5a0070d279d2007982c270a4516 (patch)
tree46b2490512e0d1c46d829f8b9af4c53b5a67d1a7 /lib
parent3d2af3adeade7dc9242442159f3cb32bc12f39c1 (diff)
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rslib: Fix decoding of shortened codes
[ Upstream commit 2034a42d1747fc1e1eeef2c6f1789c4d0762cb9c ] The decoding of shortenend codes is broken. It only works as expected if there are no erasures. When decoding with erasures, Lambda (the error and erasure locator polynomial) is initialized from the given erasure positions. The pad parameter is not accounted for by the initialisation code, and hence Lambda is initialized from incorrect erasure positions. The fix is to adjust the erasure positions by the supplied pad. Signed-off-by: Ferdinand Blomqvist <ferdinand.blomqvist@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190620141039.9874-3-ferdinand.blomqvist@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/reed_solomon/decode_rs.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/lib/reed_solomon/decode_rs.c b/lib/reed_solomon/decode_rs.c
index 0ec3f257ffdf..8eed0f9ac495 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) {