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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 <syzkaller@googlegroups.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Laura Abbott 2018-05-14 14:35:09 -07:00 committed by Greg Kroah-Hartman
parent 832016dfc3
commit 45ad559a29
1 changed files with 4 additions and 1 deletions
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5
drivers/staging/android/ion/ion.c
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@ -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);
}