[PATCH AUTOSEL 4.14 082/105] rslib: Fix handling of of caller provided syndrome

Sasha Levin
2019-07-15T14:33:49Z

From: Ferdinand Blomqvist <ferdinand.blomqvist@gmail.com>

[ Upstream commit ef4d6a8556b637ad27c8c2a2cff1dda3da38e9a9 ]

Check if the syndrome provided by the caller is zero, and act
accordingly.

Signed-off-by: Ferdinand Blomqvist <ferdinand.blomqvist@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190620141039.9874-6-ferdinand.blomqvist@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
lib/reed_solomon/decode_rs.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/reed_solomon/decode_rs.c b/lib/reed_solomon/decode_rs.c
index 8eed0f9ac495..a5d313381539 100644
--- a/lib/reed_solomon/decode_rs.c
+++ b/lib/reed_solomon/decode_rs.c
@@ -42,8 +42,18 @@
BUG_ON(pad < 0 || pad >= nn);

/* Does the caller provide the syndrome ? */
- if (s != NULL)
- goto decode;
+ if (s != NULL) {
+ for (i = 0; i < nroots; i++) {
+ /* The syndrome is in index form,
+ * so nn represents zero
+ */
+ if (s[i] != nn)
+ goto decode;
+ }
+
+ /* syndrome is zero, no errors to correct */
+ return 0;
+ }

/* form the syndromes; i.e., evaluate data(x) at roots of
* g(x) */
--
2.20.1