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@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
---
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 e74db7902549..a68329411b29 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -114,8 +114,11 @@ static struct ion_buffer *ion_buffer_create(struct ion_heap *heap,
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);
}
--
2.17.0
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