debian/patches/extra/CVE-2016-2197-ahci-null-pointer.patch

   1 From 867dcfc8c153c463090b972c2afc7b90700bab91 Mon Sep 17 00:00:00 2001
   2 From: Prasad J Pandit <pjp@fedoraproject.org>
   3 Date: Fri, 29 Jan 2016 01:18:50 +0530
   4 Subject: [PATCH 2/2] ide: ahci: add check before calling dma_memory_unmap
   5
   6 When IDE AHCI emulation uses Frame Information Structures(FIS)
   7 engine for data transfer, the mapped FIS buffer address is stored
   8 in a static 'bounce.buffer'. When a request is made to map another
   9 memory region, address_space_map() returns NULL because
  10 'bounce.buffer' is in_use. It leads to a null pointer dereference
  11 error while doing 'dma_memory_unmap'. Add a check to avoid it.
  12
  13 Reported-by: Zuozhi fzz <zuozhi.fzz@alibaba-inc.com>
  14 Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
  15 ---
  16  hw/ide/ahci.c | 16 ++++++++++------
  17  1 file changed, 10 insertions(+), 6 deletions(-)
  18
  19 diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
  20 index dd1912e..ea351fe 100644
  21 --- a/hw/ide/ahci.c
  22 +++ b/hw/ide/ahci.c
  23 @@ -661,9 +661,11 @@ static bool ahci_map_fis_address(AHCIDevice *ad)
  24
  25  static void ahci_unmap_fis_address(AHCIDevice *ad)
  26  {
  27 -    dma_memory_unmap(ad->hba->as, ad->res_fis, 256,
  28 -                     DMA_DIRECTION_FROM_DEVICE, 256);
  29 -    ad->res_fis = NULL;
  30 +    if (ad->res_fis) {
  31 +        dma_memory_unmap(ad->hba->as, ad->res_fis, 256,
  32 +                         DMA_DIRECTION_FROM_DEVICE, 256);
  33 +        ad->res_fis = NULL;
  34 +    }
  35  }
  36
  37  static bool ahci_map_clb_address(AHCIDevice *ad)
  38 @@ -677,9 +679,11 @@ static bool ahci_map_clb_address(AHCIDevice *ad)
  39
  40  static void ahci_unmap_clb_address(AHCIDevice *ad)
  41  {
  42 -    dma_memory_unmap(ad->hba->as, ad->lst, 1024,
  43 -                     DMA_DIRECTION_FROM_DEVICE, 1024);
  44 -    ad->lst = NULL;
  45 +    if (ad->lst) {
  46 +        dma_memory_unmap(ad->hba->as, ad->lst, 1024,
  47 +                         DMA_DIRECTION_FROM_DEVICE, 1024);
  48 +        ad->lst = NULL;
  49 +    }
  50  }
  51
  52  static void ahci_write_fis_sdb(AHCIState *s, NCQTransferState *ncq_tfs)
  53 --
  54 2.1.4
  55