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huthmdroth
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hw/core/loader: Fix possible crash in rom_copy()
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. This could maybe be used to inject code from a 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 Message-Id: <20190925130331.27825-1-thuth@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Thomas Huth <thuth@redhat.com> (cherry picked from commit e423455) Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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Diff for: hw/core/loader.c

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Original file line numberDiff line numberDiff line change
@@ -1240,7 +1240,7 @@ int rom_copy(uint8_t *dest, hwaddr addr, size_t size)
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if (rom->addr + rom->romsize < addr) {
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continue;
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}
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if (rom->addr > end) {
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if (rom->addr > end || rom->addr < addr) {
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break;
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}
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