[Xen-changelog] [qemu-xen stable-4.3] ide: ahci: reset ncq object to unused on error

[patchbot@xxxxxxx]

commit 4c32a1d125c7a541a0a4a95186e2af3b6d0a9004
Author:     Prasad J Pandit <pjp@xxxxxxxxxxxxxxxxx>
AuthorDate: Fri Feb 5 13:58:20 2016 +0000
Commit:     Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
CommitDate: Fri Feb 5 14:47:09 2016 +0000

    ide: ahci: reset ncq object to unused on error
    
    When processing NCQ commands, AHCI device emulation prepares a
    NCQ transfer object; To which an aio control block(aiocb) object
    is assigned in 'execute_ncq_command'. In case, when the NCQ
    command is invalid, the 'aiocb' object is not assigned, and NCQ
    transfer object is left as 'used'. This leads to a use after
    free kind of error in 'bdrv_aio_cancel_async' via 'ahci_reset_port'.
    Reset NCQ transfer object to 'unused' to avoid it.
    
    [Maintainer edit: s/ACHI/AHCI/ in the commit message. --js]
    
    Reported-by: Qinghao Tang <luodalongde@xxxxxxxxx>
    Signed-off-by: Prasad J Pandit <pjp@xxxxxxxxxxxxxxxxx>
    Reviewed-by: John Snow <jsnow@xxxxxxxxxx>
    Message-id: 1452282511-4116-1-git-send-email-ppandit@xxxxxxxxxx
    Signed-off-by: John Snow <jsnow@xxxxxxxxxx>
    Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 hw/ide/ahci.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
index 67562db..6a7e2fb 100644
--- a/hw/ide/ahci.c
+++ b/hw/ide/ahci.c
@@ -722,6 +722,7 @@ static void ncq_cb(void *opaque, int ret)
         ide_state->error = ABRT_ERR;
         ide_state->status = READY_STAT | ERR_STAT;
         ncq_tfs->drive->port_regs.scr_err |= (1 << ncq_tfs->tag);
+        ncq_tfs->used = 0;
     } else {
         ide_state->status = READY_STAT | SEEK_STAT;
     }
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#stable-4.3

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