binder: additional transaction error logs

Log readable and specific error messages whenever a transaction failure
happens. This will ensure better context is given to regular users about
these unique error cases, without having to decode a cryptic log.

Acked-by: Todd Kjos <tkjos@google.com>
Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20220429235644.697372-6-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 44 insertions, 4 deletions

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 88f502848397..d9253b2a7bd9 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -147,6 +147,9 @@ static __printf(2, 3) void binder_debug(int mask, const char *format, ...)
 	}
 }
 
+#define binder_txn_error(x...) \
+	binder_debug(BINDER_DEBUG_FAILED_TRANSACTION, x)
+
 static __printf(1, 2) void binder_user_error(const char *format, ...)
 {
 	struct va_format vaf;
@@ -2834,6 +2837,8 @@ static void binder_transaction(struct binder_proc *proc,
 		if (target_thread == NULL) {
 			/* annotation for sparse */
 			__release(&target_thread->proc->inner_lock);
+			binder_txn_error("%d:%d reply target not found\n",
+				thread->pid, proc->pid);
 			return_error = BR_DEAD_REPLY;
 			return_error_line = __LINE__;
 			goto err_dead_binder;
@@ -2899,6 +2904,8 @@ static void binder_transaction(struct binder_proc *proc,
 			}
 		}
 		if (!target_node) {
+			binder_txn_error("%d:%d cannot find target node\n",
+				thread->pid, proc->pid);
 			/*
 			 * return_error is set above
 			 */
@@ -2908,6 +2915,8 @@ static void binder_transaction(struct binder_proc *proc,
 		}
 		e->to_node = target_node->debug_id;
 		if (WARN_ON(proc == target_proc)) {
+			binder_txn_error("%d:%d self transactions not allowed\n",
+				thread->pid, proc->pid);
 			return_error = BR_FAILED_REPLY;
 			return_error_param = -EINVAL;
 			return_error_line = __LINE__;
@@ -2915,6 +2924,8 @@ static void binder_transaction(struct binder_proc *proc,
 		}
 		if (security_binder_transaction(proc->cred,
 						target_proc->cred) < 0) {
+			binder_txn_error("%d:%d transaction credentials failed\n",
+				thread->pid, proc->pid);
 			return_error = BR_FAILED_REPLY;
 			return_error_param = -EPERM;
 			return_error_line = __LINE__;
@@ -2986,6 +2997,8 @@ static void binder_transaction(struct binder_proc *proc,
 	/* TODO: reuse incoming transaction for reply */
 	t = kzalloc(sizeof(*t), GFP_KERNEL);
 	if (t == NULL) {
+		binder_txn_error("%d:%d cannot allocate transaction\n",
+			thread->pid, proc->pid);
 		return_error = BR_FAILED_REPLY;
 		return_error_param = -ENOMEM;
 		return_error_line = __LINE__;
@@ -2997,6 +3010,8 @@ static void binder_transaction(struct binder_proc *proc,
 
 	tcomplete = kzalloc(sizeof(*tcomplete), GFP_KERNEL);
 	if (tcomplete == NULL) {
+		binder_txn_error("%d:%d cannot allocate work for transaction\n",
+			thread->pid, proc->pid);
 		return_error = BR_FAILED_REPLY;
 		return_error_param = -ENOMEM;
 		return_error_line = __LINE__;
@@ -3043,6 +3058,8 @@ static void binder_transaction(struct binder_proc *proc,
 		security_cred_getsecid(proc->cred, &secid);
 		ret = security_secid_to_secctx(secid, &secctx, &secctx_sz);
 		if (ret) {
+			binder_txn_error("%d:%d failed to get security context\n",
+				thread->pid, proc->pid);
 			return_error = BR_FAILED_REPLY;
 			return_error_param = ret;
 			return_error_line = __LINE__;
@@ -3051,7 +3068,8 @@ static void binder_transaction(struct binder_proc *proc,
 		added_size = ALIGN(secctx_sz, sizeof(u64));
 		extra_buffers_size += added_size;
 		if (extra_buffers_size < added_size) {
-			/* integer overflow of extra_buffers_size */
+			binder_txn_error("%d:%d integer overflow of extra_buffers_size\n",
+				thread->pid, proc->pid);
 			return_error = BR_FAILED_REPLY;
 			return_error_param = -EINVAL;
 			return_error_line = __LINE__;
@@ -3065,9 +3083,15 @@ static void binder_transaction(struct binder_proc *proc,
 		tr->offsets_size, extra_buffers_size,
 		!reply && (t->flags & TF_ONE_WAY), current->tgid);
 	if (IS_ERR(t->buffer)) {
-		/*
-		 * -ESRCH indicates VMA cleared. The target is dying.
-		 */
+		char *s;
+
+		ret = PTR_ERR(t->buffer);
+		s = (ret == -ESRCH) ? ": vma cleared, target dead or dying"
+			: (ret == -ENOSPC) ? ": no space left"
+			: (ret == -ENOMEM) ? ": memory allocation failed"
+			: "";
+		binder_txn_error("cannot allocate buffer%s", s);
+
 		return_error_param = PTR_ERR(t->buffer);
 		return_error = return_error_param == -ESRCH ?
 			BR_DEAD_REPLY : BR_FAILED_REPLY;
@@ -3150,6 +3174,8 @@ static void binder_transaction(struct binder_proc *proc,
 						  t->buffer,
 						  buffer_offset,
 						  sizeof(object_offset))) {
+			binder_txn_error("%d:%d copy offset from buffer failed\n",
+				thread->pid, proc->pid);
 			return_error = BR_FAILED_REPLY;
 			return_error_param = -EINVAL;
 			return_error_line = __LINE__;
@@ -3208,6 +3234,8 @@ static void binder_transaction(struct binder_proc *proc,
 							t->buffer,
 							object_offset,
 							fp, sizeof(*fp))) {
+				binder_txn_error("%d:%d translate binder failed\n",
+					thread->pid, proc->pid);
 				return_error = BR_FAILED_REPLY;
 				return_error_param = ret;
 				return_error_line = __LINE__;
@@ -3225,6 +3253,8 @@ static void binder_transaction(struct binder_proc *proc,
 							t->buffer,
 							object_offset,
 							fp, sizeof(*fp))) {
+				binder_txn_error("%d:%d translate handle failed\n",
+					thread->pid, proc->pid);
 				return_error = BR_FAILED_REPLY;
 				return_error_param = ret;
 				return_error_line = __LINE__;
@@ -3245,6 +3275,8 @@ static void binder_transaction(struct binder_proc *proc,
 							t->buffer,
 							object_offset,
 							fp, sizeof(*fp))) {
+				binder_txn_error("%d:%d translate fd failed\n",
+					thread->pid, proc->pid);
 				return_error = BR_FAILED_REPLY;
 				return_error_param = ret;
 				return_error_line = __LINE__;
@@ -3314,6 +3346,8 @@ static void binder_transaction(struct binder_proc *proc,
 								  object_offset,
 								  fda, sizeof(*fda));
 			if (ret) {
+				binder_txn_error("%d:%d translate fd array failed\n",
+					thread->pid, proc->pid);
 				return_error = BR_FAILED_REPLY;
 				return_error_param = ret > 0 ? -EINVAL : ret;
 				return_error_line = __LINE__;
@@ -3341,6 +3375,8 @@ static void binder_transaction(struct binder_proc *proc,
 				(const void __user *)(uintptr_t)bp->buffer,
 				bp->length);
 			if (ret) {
+				binder_txn_error("%d:%d deferred copy failed\n",
+					thread->pid, proc->pid);
 				return_error = BR_FAILED_REPLY;
 				return_error_param = ret;
 				return_error_line = __LINE__;
@@ -3364,6 +3400,8 @@ static void binder_transaction(struct binder_proc *proc,
 							t->buffer,
 							object_offset,
 							bp, sizeof(*bp))) {
+				binder_txn_error("%d:%d failed to fixup parent\n",
+					thread->pid, proc->pid);
 				return_error = BR_FAILED_REPLY;
 				return_error_param = ret;
 				return_error_line = __LINE__;
@@ -3471,6 +3509,8 @@ static void binder_transaction(struct binder_proc *proc,
 	return;
 
 err_dead_proc_or_thread:
+	binder_txn_error("%d:%d dead process or thread\n",
+		thread->pid, proc->pid);
 	return_error_line = __LINE__;
 	binder_dequeue_work(proc, tcomplete);
 err_translate_failed: