[Qemu-devel] [PATCH] ide: ahci: reset ncq object to unused on error

[P J P <ppandit@redhat.com>]

From: Prasad J Pandit <pjp@fedoraproject.org>

When processing NCQ commands, ACHI 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 error in 'bdrv_aio_cancel_async' via 'ahci_reset_port'.
Reset NCQ transfer object to 'unused' to avoid it.

Reported-by: Qinghao Tang <luodalongde@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/ide/ahci.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
index dd1912e..e359127 100644
--- a/hw/ide/ahci.c
+++ b/hw/ide/ahci.c
@@ -1014,6 +1014,7 @@ static void execute_ncq_command(NCQTransferState *ncq_tfs)
         DPRINTF(port, "error: unsupported NCQ command (0x%02x) received\n",
                 ncq_tfs->cmd);
         qemu_sglist_destroy(&ncq_tfs->sglist);
+        ncq_tfs->used = 0;
         ncq_err(ncq_tfs);
     }
 }
@@ -1081,6 +1082,7 @@ static void process_ncq_command(AHCIState *s, int port, uint8_t *cmd_fis,
                      "is smaller than the requested size (0x%zx)",
                      ncq_tfs->sglist.size, size);
         qemu_sglist_destroy(&ncq_tfs->sglist);
+        ncq_tfs->used = 0;
         ncq_err(ncq_tfs);
         ahci_trigger_irq(ad->hba, ad, PORT_IRQ_OVERFLOW);
         return;
-- 
2.4.3