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authorTodd Kjos <tkjos@android.com>2019-12-13 12:25:31 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-12-14 09:10:47 +0100
commit16981742717b04644a41052570fb502682a315d2 (patch)
tree81e6f0d2bf4db7382e7aaf6064ffd0e481dca03b /drivers/android
parent3e42fe5c73108a6e68c98bc0df937888e35af97f (diff)
downloadlinux-16981742717b04644a41052570fb502682a315d2.tar.gz
binder: fix incorrect calculation for num_valid
For BINDER_TYPE_PTR and BINDER_TYPE_FDA transactions, the
num_valid local was calculated incorrectly causing the
range check in binder_validate_ptr() to miss out-of-bounds
offsets.

Fixes: bde4a19fc04f ("binder: use userspace pointer as base of buffer space")
Signed-off-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191213202531.55010-1-tkjos@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/android')
-rw-r--r--drivers/android/binder.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index e9bc9fcc7ea5..b2dad43dbf82 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -3310,7 +3310,7 @@ static void binder_transaction(struct binder_proc *proc,
 			binder_size_t parent_offset;
 			struct binder_fd_array_object *fda =
 				to_binder_fd_array_object(hdr);
-			size_t num_valid = (buffer_offset - off_start_offset) *
+			size_t num_valid = (buffer_offset - off_start_offset) /
 						sizeof(binder_size_t);
 			struct binder_buffer_object *parent =
 				binder_validate_ptr(target_proc, t->buffer,
@@ -3384,7 +3384,7 @@ static void binder_transaction(struct binder_proc *proc,
 				t->buffer->user_data + sg_buf_offset;
 			sg_buf_offset += ALIGN(bp->length, sizeof(u64));
 
-			num_valid = (buffer_offset - off_start_offset) *
+			num_valid = (buffer_offset - off_start_offset) /
 					sizeof(binder_size_t);
 			ret = binder_fixup_parent(t, thread, bp,
 						  off_start_offset,