This is a note to let you know that I've just added the patch titled binder: don't detect sender/target during buffer cleanup to the 5.4-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: binder-don-t-detect-sender-target-during-buffer-cleanup.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 32e9f56a96d8d0f23cb2aeb2a3cd18d40393e787 Mon Sep 17 00:00:00 2001 From: Todd Kjos <tkjos@xxxxxxxxxx> Date: Fri, 15 Oct 2021 16:38:11 -0700 Subject: binder: don't detect sender/target during buffer cleanup From: Todd Kjos <tkjos@xxxxxxxxxx> commit 32e9f56a96d8d0f23cb2aeb2a3cd18d40393e787 upstream. When freeing txn buffers, binder_transaction_buffer_release() attempts to detect whether the current context is the target by comparing current->group_leader to proc->tsk. This is an unreliable test. Instead explicitly pass an 'is_failure' boolean. Detecting the sender was being used as a way to tell if the transaction failed to be sent. When cleaning up after failing to send a transaction, there is no need to close the fds associated with a BINDER_TYPE_FDA object. Now 'is_failure' can be used to accurately detect this case. Fixes: 44d8047f1d87 ("binder: use standard functions to allocate fds") Cc: stable <stable@xxxxxxxxxxxxxxx> Acked-by: Christian Brauner <christian.brauner@xxxxxxxxxx> Signed-off-by: Todd Kjos <tkjos@xxxxxxxxxx> Link: https://lore.kernel.org/r/20211015233811.3532235-1-tkjos@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/android/binder.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2257,7 +2257,7 @@ static void binder_transaction_buffer_re binder_dec_node(buffer->target_node, 1, 0); off_start_offset = ALIGN(buffer->data_size, sizeof(void *)); - off_end_offset = is_failure ? failed_at : + off_end_offset = is_failure && failed_at ? failed_at : off_start_offset + buffer->offsets_size; for (buffer_offset = off_start_offset; buffer_offset < off_end_offset; buffer_offset += sizeof(binder_size_t)) { @@ -2343,9 +2343,8 @@ static void binder_transaction_buffer_re binder_size_t fd_buf_size; binder_size_t num_valid; - if (proc->tsk != current->group_leader) { + if (is_failure) { /* - * Nothing to do if running in sender context * The fd fixups have not been applied so no * fds need to be closed. */ @@ -3548,6 +3547,7 @@ err_invalid_target_handle: * binder_free_buf() - free the specified buffer * @proc: binder proc that owns buffer * @buffer: buffer to be freed + * @is_failure: failed to send transaction * * If buffer for an async transaction, enqueue the next async * transaction from the node. @@ -3557,7 +3557,7 @@ err_invalid_target_handle: static void binder_free_buf(struct binder_proc *proc, struct binder_thread *thread, - struct binder_buffer *buffer) + struct binder_buffer *buffer, bool is_failure) { binder_inner_proc_lock(proc); if (buffer->transaction) { @@ -3585,7 +3585,7 @@ binder_free_buf(struct binder_proc *proc binder_node_inner_unlock(buf_node); } trace_binder_transaction_buffer_release(buffer); - binder_transaction_buffer_release(proc, thread, buffer, 0, false); + binder_transaction_buffer_release(proc, thread, buffer, 0, is_failure); binder_alloc_free_buf(&proc->alloc, buffer); } @@ -3786,7 +3786,7 @@ static int binder_thread_write(struct bi proc->pid, thread->pid, (u64)data_ptr, buffer->debug_id, buffer->transaction ? "active" : "finished"); - binder_free_buf(proc, thread, buffer); + binder_free_buf(proc, thread, buffer, false); break; } @@ -4474,7 +4474,7 @@ retry: buffer->transaction = NULL; binder_cleanup_transaction(t, "fd fixups failed", BR_FAILED_REPLY); - binder_free_buf(proc, thread, buffer); + binder_free_buf(proc, thread, buffer, true); binder_debug(BINDER_DEBUG_FAILED_TRANSACTION, "%d:%d %stransaction %d fd fixups failed %d/%d, line %d\n", proc->pid, thread->pid, Patches currently in stable-queue which might be from tkjos@xxxxxxxxxx are queue-5.4/binder-don-t-detect-sender-target-during-buffer-cleanup.patch