[PATCH] binder: Set end of SG buffer area properly.

[Martijn Coenen <maco@android.com>]

In case the target node requests a security context, the
extra_buffers_size is increased with the size of the security context.
But, that size is not available for use by regular scatter-gather
buffers; make sure the ending of that buffer is marked correctly.

Acked-by: Todd Kjos <tkjos@google.com>
Fixes: ec74136ded79 ("binder: create node flag to request sender's
security context")
Signed-off-by: Martijn Coenen <maco@android.com>
Cc: stable@vger.kernel.org # 5.1+
---
 drivers/android/binder.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 38a59a630cd4c..5bde08603fbc2 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -3239,7 +3239,8 @@ static void binder_transaction(struct binder_proc *proc,
 	buffer_offset = off_start_offset;
 	off_end_offset = off_start_offset + tr->offsets_size;
 	sg_buf_offset = ALIGN(off_end_offset, sizeof(void *));
-	sg_buf_end_offset = sg_buf_offset + extra_buffers_size;
+	sg_buf_end_offset = sg_buf_offset + extra_buffers_size -
+		ALIGN(secctx_sz, sizeof(u64));
 	off_min = 0;
 	for (buffer_offset = off_start_offset; buffer_offset < off_end_offset;
 	     buffer_offset += sizeof(binder_size_t)) {
-- 
2.22.0.410.gd8fdbe21b5-goog