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loader: Check access size when calling rom_ptr() to avoid crashes

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The rom_ptr() function allows direct access to the ROM blobs that we
load during startup. However, there are currently no checks for the
size of the accesses, so it's currently possible to crash QEMU for
example with:

$ echo "Insane in the mainframe" > /tmp/test.txt
$ s390x-softmmu/qemu-system-s390x -kernel /tmp/test.txt -append xyz
Segmentation fault (core dumped)
$ s390x-softmmu/qemu-system-s390x -kernel /tmp/test.txt -initrd /tmp/test.txt
Segmentation fault (core dumped)
$ echo -n HdrS > /tmp/hdr.txt
$ sparc64-softmmu/qemu-system-sparc64 -kernel /tmp/hdr.txt -initrd /tmp/hdr.txt
Segmentation fault (core dumped)

We need a possibility to check the size of the ROM area that we want
to access, thus let's add a size parameter to the rom_ptr() function
to avoid these problems.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1530005740-25254-1-git-send-email-thuth@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
Thomas Huth 2018-06-26 11:35:40 +02:00 • committed by Cornelia Huck
parent 76ed4b18de
commit 0f0f8b611e
7 changed files with 27 additions and 19 deletions
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4
hw/sparc/sun4m.c
View file

@ -272,8 +272,8 @@ static unsigned long sun4m_load_kernel(const char *kernel_filename,
}
if (initrd_size > 0) {
for (i = 0; i < 64 * TARGET_PAGE_SIZE; i += TARGET_PAGE_SIZE) {
ptr = rom_ptr(KERNEL_LOAD_ADDR + i);
if (ldl_p(ptr) == 0x48647253) { // HdrS
ptr = rom_ptr(KERNEL_LOAD_ADDR + i, 24);
if (ptr && ldl_p(ptr) == 0x48647253) { /* HdrS */
stl_p(ptr + 16, INITRD_LOAD_ADDR);
stl_p(ptr + 20, initrd_size);
break;