[Xen-changelog] [qemu-upstream-unstable] ide: Check array bounds before writing to io_buffer (CVE-2015-5154)

[patchbot@xxxxxxx]

commit aaaa1f4499a81204a96ed8273ee3d90d684102ed
Author:     Kevin Wolf <kwolf@xxxxxxxxxx>
AuthorDate: Sun Jul 26 23:42:53 2015 -0400
Commit:     Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
CommitDate: Wed Jul 29 15:25:09 2015 +0000

    ide: Check array bounds before writing to io_buffer (CVE-2015-5154)
    
    If the end_transfer_func of a command is called because enough data has
    been read or written for the current PIO transfer, and it fails to
    correctly call the command completion functions, the DRQ bit in the
    status register and s->end_transfer_func may remain set. This allows the
    guest to access further bytes in s->io_buffer beyond s->data_end, and
    eventually overflowing the io_buffer.
    
    One case where this currently happens is emulation of the ATAPI command
    START STOP UNIT.
    
    This patch fixes the problem by adding explicit array bounds checks
    before accessing the buffer instead of relying on end_transfer_func to
    function correctly.
    
    upstream-commit-id: d2ff85854512574e7209f295e87b0835d5b032c6
    
    Cc: qemu-stable@xxxxxxxxxx
    Signed-off-by: Kevin Wolf <kwolf@xxxxxxxxxx>
    Reviewed-by: John Snow <jsnow@xxxxxxxxxx>
    Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 hw/ide/core.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index d4af5e2..a4467e9 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -2013,6 +2013,10 @@ void ide_data_writew(void *opaque, uint32_t addr, 
uint32_t val)
     }
 
     p = s->data_ptr;
+    if (p + 2 > s->data_end) {
+        return;
+    }
+
     *(uint16_t *)p = le16_to_cpu(val);
     p += 2;
     s->data_ptr = p;
@@ -2034,6 +2038,10 @@ uint32_t ide_data_readw(void *opaque, uint32_t addr)
     }
 
     p = s->data_ptr;
+    if (p + 2 > s->data_end) {
+        return 0;
+    }
+
     ret = cpu_to_le16(*(uint16_t *)p);
     p += 2;
     s->data_ptr = p;
@@ -2055,6 +2063,10 @@ void ide_data_writel(void *opaque, uint32_t addr, 
uint32_t val)
     }
 
     p = s->data_ptr;
+    if (p + 4 > s->data_end) {
+        return;
+    }
+
     *(uint32_t *)p = le32_to_cpu(val);
     p += 4;
     s->data_ptr = p;
@@ -2076,6 +2088,10 @@ uint32_t ide_data_readl(void *opaque, uint32_t addr)
     }
 
     p = s->data_ptr;
+    if (p + 4 > s->data_end) {
+        return 0;
+    }
+
     ret = cpu_to_le32(*(uint32_t *)p);
     p += 4;
     s->data_ptr = p;
--
generated by git-patchbot for /home/xen/git/qemu-upstream-unstable.git

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