From 45ad559a29629cb1c64ee636563c69b71524f077 Mon Sep 17 00:00:00 2001 From: Laura Abbott Date: Mon, 14 May 2018 14:35:09 -0700 Subject: [PATCH] staging: android: ion: Switch to pr_warn_once in ion_buffer_destroy Syzbot reported yet another warning with Ion: WARNING: CPU: 0 PID: 1467 at drivers/staging/android/ion/ion.c:122 ion_buffer_destroy+0xd4/0x190 drivers/staging/android/ion/ion.c:122 Kernel panic - not syncing: panic_on_warn set ... This is catching that a buffer was freed with an existing kernel mapping still present. This can be easily be triggered from userspace by calling DMA_BUF_SYNC_START without calling DMA_BUF_SYNC_END. Switch to a single pr_warn_once to indicate the error without being disruptive. Reported-by: syzbot+cd8bcd40cb049efa2770@syzkaller.appspotmail.com Reported-by: syzbot Signed-off-by: Laura Abbott Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/ion/ion.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c index af682cb..9d1109e 100644 --- a/drivers/staging/android/ion/ion.c +++ b/drivers/staging/android/ion/ion.c @@ -111,8 +111,11 @@ err2: void ion_buffer_destroy(struct ion_buffer *buffer) { - if (WARN_ON(buffer->kmap_cnt > 0)) + if (buffer->kmap_cnt > 0) { + pr_warn_once("%s: buffer still mapped in the kernel\n", + __func__); buffer->heap->ops->unmap_kernel(buffer->heap, buffer); + } buffer->heap->ops->free(buffer); kfree(buffer); } -- 2.7.4