[Xen-changelog] [qemu-xen-traditional stable-4.7] cirrus: fix oob access issue (CVE-2017-2615)

[patchbot@xxxxxxx]

commit a20cf3a6edd051f2f2eb734a7bcda6c6246740ff
Author:     Li Qiang <liqiang6-s@xxxxxx>
AuthorDate: Mon Feb 13 15:22:15 2017 +0000
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Wed Feb 22 16:28:12 2017 +0000

    cirrus: fix oob access issue (CVE-2017-2615)
    
    When doing bitblt copy in backward mode, we should minus the
    blt width first just like the adding in the forward mode. This
    can avoid the oob access of the front of vga's vram.
    
    This is XSA-208.
    
    upstream-commit-id: 62d4c6bd5263bb8413a06c80144fc678df6dfb64
    
    Signed-off-by: Li Qiang <liqiang6-s@xxxxxx>
    
    { kraxel: with backward blits (negative pitch) addr is the topmost
              address, so check it as-is against vram size ]
    
    [ This is CVE-2017-2615 / XSA-208  - Ian Jackson ]
    
    Cc: qemu-stable@xxxxxxxxxx
    Cc: P J P <ppandit@xxxxxxxxxx>
    Cc: Laszlo Ersek <lersek@xxxxxxxxxx>
    Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Cc: Wolfgang Bumiller <w.bumiller@xxxxxxxxxxx>
    Fixes: d3532a0db02296e687711b8cdc7791924efccea0 (CVE-2014-8106)
    Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
    Message-id: 1485938101-26602-1-git-send-email-kraxel@xxxxxxxxxx
    Reviewed-by: Laszlo Ersek <lersek@xxxxxxxxxx>
    Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
    Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
    (cherry picked from commit c4018bc4d638918b3f8fb49dd3b379abb5658ee1)
    (cherry picked from commit a1d57bb66d5f7e3a86e47c01431c823e217b23ab)
---
 hw/cirrus_vga.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/hw/cirrus_vga.c b/hw/cirrus_vga.c
index e6c3893..364e22d 100644
--- a/hw/cirrus_vga.c
+++ b/hw/cirrus_vga.c
@@ -308,10 +308,9 @@ static bool blit_region_is_unsafe(struct CirrusVGAState *s,
 {
     if (pitch < 0) {
         int64_t min = addr
-            + ((int64_t)s->cirrus_blt_height-1) * pitch;
-        int32_t max = addr
-            + s->cirrus_blt_width;
-        if (min < 0 || max >= s->vram_size) {
+            + ((int64_t)s->cirrus_blt_height - 1) * pitch
+            - s->cirrus_blt_width;
+        if (min < -1 || addr >= s->vram_size) {
             return true;
         }
     } else {
--
generated by git-patchbot for /home/xen/git/qemu-xen-traditional.git#stable-4.7

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