@state_var is copied as part of the descriptor copying via
memcpy(). This is not allowed because @state_var is an atomic type,
which in some implementations may contain a spinlock.
Avoid using memcpy() with @state_var by explicitly copying the other
fields of the descriptor. @state_var is set using atomic set
operator before returning.
Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer")
Signed-off-by: John Ogness <john.ogn...@linutronix.de>
---
kernel/printk/printk_ringbuffer.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/printk/printk_ringbuffer.c
b/kernel/printk/printk_ringbuffer.c
index 88f7dd4cb0c1..11b860ad5264 100644
--- a/kernel/printk/printk_ringbuffer.c
+++ b/kernel/printk/printk_ringbuffer.c
@@ -412,9 +412,14 @@ static enum desc_state desc_read(struct prb_desc_ring
*desc_ring,
/*
* Copy the descriptor data. The data is not valid until the
- * state has been re-checked.
+ * state has been re-checked. A memcpy() for all of @desc
+ * cannot be used because of the atomic_t @state_var field.
*/
- memcpy(desc_out, desc, sizeof(*desc_out)); /* LMM(desc_read:C) */
+ memcpy(&desc_out->info, &desc->info, sizeof(desc_out->info)); /*
LMM(desc_read:C) */
+ memcpy(&desc_out->text_blk_lpos, &desc->text_blk_lpos,
+ sizeof(desc_out->text_blk_lpos)); /* also part of desc_read:C */
+ memcpy(&desc_out->dict_blk_lpos, &desc->dict_blk_lpos,
+ sizeof(desc_out->dict_blk_lpos)); /* also part of desc_read:C */
/*
* 1. Guarantee the descriptor content is loaded before re-checking
--
2.19.0
