From: Thomas Huth Date: Wed, 25 Sep 2019 14:16:43 +0200 Subject: hw/core/loader: Fix possible crash in rom_copy() Git-commit: e423455c4f23a1a828901c78fe6d03b7dde79319 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 Signed-off-by: Thomas Huth Signed-off-by: Bruce Rogers --- hw/core/loader.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/core/loader.c b/hw/core/loader.c index 425bf69a9968765b4604a442eb0a..838a34174ac2039d55f557fa427a 100644 --- a/hw/core/loader.c +++ b/hw/core/loader.c @@ -1242,7 +1242,7 @@ int rom_copy(uint8_t *dest, hwaddr addr, size_t size) if (rom->addr + rom->romsize < addr) { continue; } - if (rom->addr > end) { + if (rom->addr > end || rom->addr < addr) { break; }