This is a note to let you know that I've just added the patch titled ANDROID: binder: Add strong ref checks to the 4.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: android-binder-add-strong-ref-checks.patch and it can be found in the queue-4.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 0a3ffab93fe52530602fe47cd74802cffdb19c05 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= <arve@xxxxxxxxxxx> Date: Mon, 24 Oct 2016 15:20:29 +0200 Subject: ANDROID: binder: Add strong ref checks MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Arve Hjønnevåg <arve@xxxxxxxxxxx> commit 0a3ffab93fe52530602fe47cd74802cffdb19c05 upstream. Prevent using a binder_ref with only weak references where a strong reference is required. Signed-off-by: Arve Hjønnevåg <arve@xxxxxxxxxxx> Signed-off-by: Martijn Coenen <maco@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/android/binder.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1003,7 +1003,7 @@ static int binder_dec_node(struct binder static struct binder_ref *binder_get_ref(struct binder_proc *proc, - uint32_t desc) + u32 desc, bool need_strong_ref) { struct rb_node *n = proc->refs_by_desc.rb_node; struct binder_ref *ref; @@ -1011,12 +1011,16 @@ static struct binder_ref *binder_get_ref while (n) { ref = rb_entry(n, struct binder_ref, rb_node_desc); - if (desc < ref->desc) + if (desc < ref->desc) { n = n->rb_left; - else if (desc > ref->desc) + } else if (desc > ref->desc) { n = n->rb_right; - else + } else if (need_strong_ref && !ref->strong) { + binder_user_error("tried to use weak ref as strong ref\n"); + return NULL; + } else { return ref; + } } return NULL; } @@ -1286,7 +1290,10 @@ static void binder_transaction_buffer_re } break; case BINDER_TYPE_HANDLE: case BINDER_TYPE_WEAK_HANDLE: { - struct binder_ref *ref = binder_get_ref(proc, fp->handle); + struct binder_ref *ref; + + ref = binder_get_ref(proc, fp->handle, + fp->type == BINDER_TYPE_HANDLE); if (ref == NULL) { pr_err("transaction release %d bad handle %d\n", @@ -1381,7 +1388,7 @@ static void binder_transaction(struct bi if (tr->target.handle) { struct binder_ref *ref; - ref = binder_get_ref(proc, tr->target.handle); + ref = binder_get_ref(proc, tr->target.handle, true); if (ref == NULL) { binder_user_error("%d:%d got transaction to invalid handle\n", proc->pid, thread->pid); @@ -1590,7 +1597,10 @@ static void binder_transaction(struct bi } break; case BINDER_TYPE_HANDLE: case BINDER_TYPE_WEAK_HANDLE: { - struct binder_ref *ref = binder_get_ref(proc, fp->handle); + struct binder_ref *ref; + + ref = binder_get_ref(proc, fp->handle, + fp->type == BINDER_TYPE_HANDLE); if (ref == NULL) { binder_user_error("%d:%d got transaction with invalid handle, %d\n", @@ -1801,7 +1811,9 @@ static int binder_thread_write(struct bi ref->desc); } } else - ref = binder_get_ref(proc, target); + ref = binder_get_ref(proc, target, + cmd == BC_ACQUIRE || + cmd == BC_RELEASE); if (ref == NULL) { binder_user_error("%d:%d refcount change on invalid ref %d\n", proc->pid, thread->pid, target); @@ -1997,7 +2009,7 @@ static int binder_thread_write(struct bi if (get_user(cookie, (binder_uintptr_t __user *)ptr)) return -EFAULT; ptr += sizeof(binder_uintptr_t); - ref = binder_get_ref(proc, target); + ref = binder_get_ref(proc, target, false); if (ref == NULL) { binder_user_error("%d:%d %s invalid ref %d\n", proc->pid, thread->pid, Patches currently in stable-queue which might be from arve@xxxxxxxxxxx are queue-4.8/android-binder-add-strong-ref-checks.patch queue-4.8/android-binder-clear-binder-and-cookie-when-setting-handle-in-flat-binder-struct.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html