Re: [PATCH] hw/core/loader: Fix possible crash in rom_copy()

[Paolo Bonzini <pbonzini@redhat.com>]

On 25/09/19 15:22, Michael S. Tsirkin wrote:
>> Both, "rom->addr" and "addr" are derived from the binary image
>> that can be loaded with the "-kernel" paramer. The code in
>> rom_copy() then calculates:
>> 
>>     d = dest + (rom->addr - addr);
>> 
>> and uses "d" as destination in a memcpy() some lines later. Now with
>> bad kernel images, it is possible that rom->addr is smaller than addr,
>> thus "rom->addr - addr" gets negative and the memcpy() then tries to
>> copy contents from the image to a bad memory location. In the best case,
>> this just crashes QEMU, in the worst case, this could maybe be used to
>> inject code from the kernel image into the QEMU binary, so we better fix
>> it with an additional sanity check here.
>> 
>> Cc: qemu-stable@nongnu.org
>> Reported-by: Guangming Liu
>> Buglink: https://bugs.launchpad.net/qemu/+bug/1844635
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Queued, thanks.

Paolo