On Wed, Nov 7, 2018 at 10:42 PM Keith Busch [off-list ref] wrote:
quoted hunk ↗ jump to hunk
If the kernel allocates a bounce buffer for user read data, this memory
needs to be cleared before copying it to the user, otherwise it may leak
kernel memory to user space.
Signed-off-by: Keith Busch <redacted>
---
block/bio.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/block/bio.c b/block/bio.c
index d5368a445561..a50d59236b19 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1260,6 +1260,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
if (ret)
goto cleanup;
} else {
+ zero_fill_bio(bio);
iov_iter_advance(iter, bio->bi_iter.bi_size);
}
This way looks inefficient because zero fill should only be required
for short READ.
Thanks,
Ming Lei