From 4367a20cc442c56b05611b4224de9a61908f9eac Mon Sep 17 00:00:00 2001 From: Mauro Matteo Cascella Date: Mon, 11 Jul 2022 14:33:16 +0200 Subject: [PATCH] scsi/lsi53c895a: really fix use-after-free in lsi_do_msgout (CVE-2022-0216) Set current_req to NULL, not current_req->req, to prevent reusing a free'd buffer in case of repeated SCSI cancel requests. Also apply the fix to CLEAR QUEUE and BUS DEVICE RESET messages as well, since they also cancel the request. Thanks to Alexander Bulekov for providing a reproducer. Fixes: CVE-2022-0216 Resolves: https://gitlab.com/qemu-project/qemu/-/issues/972 Signed-off-by: Mauro Matteo Cascella Tested-by: Alexander Bulekov Message-Id: <20220711123316.421279-1-mcascell@redhat.com> Signed-off-by: Paolo Bonzini --- hw/scsi/lsi53c895a.c | 3 +- tests/qtest/fuzz-lsi53c895a-test.c | 76 ++++++++++++++++++++++++++++++ 2 files changed, 78 insertions(+), 1 deletion(-) diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c index 99ea42d49b..ad5f5e5f39 100644 --- a/hw/scsi/lsi53c895a.c +++ b/hw/scsi/lsi53c895a.c @@ -1030,7 +1030,7 @@ static void lsi_do_msgout(LSIState *s) trace_lsi_do_msgout_abort(current_tag); if (current_req && current_req->req) { scsi_req_cancel(current_req->req); - current_req->req = NULL; + current_req = NULL; } lsi_disconnect(s); break; @@ -1056,6 +1056,7 @@ static void lsi_do_msgout(LSIState *s) /* clear the current I/O process */ if (s->current) { scsi_req_cancel(s->current->req); + current_req = NULL; } /* As the current implemented devices scsi_disk and scsi_generic diff --git a/tests/qtest/fuzz-lsi53c895a-test.c b/tests/qtest/fuzz-lsi53c895a-test.c index 2e8e67859e..b23d3ecf45 100644 --- a/tests/qtest/fuzz-lsi53c895a-test.c +++ b/tests/qtest/fuzz-lsi53c895a-test.c @@ -8,6 +8,79 @@ #include "qemu/osdep.h" #include "libqtest.h" +/* + * This used to trigger a UAF in lsi_do_msgout() + * https://gitlab.com/qemu-project/qemu/-/issues/972 + */ +static void test_lsi_do_msgout_cancel_req(void) +{ + QTestState *s; + + if (sizeof(void *) == 4) { + g_test_skip("memory size too big for 32-bit build"); + return; + } + + s = qtest_init("-M q35 -m 4G -display none -nodefaults " + "-device lsi53c895a,id=scsi " + "-device scsi-hd,drive=disk0 " + "-drive file=null-co://,id=disk0,if=none,format=raw"); + + qtest_outl(s, 0xcf8, 0x80000810); + qtest_outl(s, 0xcf8, 0xc000); + qtest_outl(s, 0xcf8, 0x80000810); + qtest_outw(s, 0xcfc, 0x7); + qtest_outl(s, 0xcf8, 0x80000810); + qtest_outl(s, 0xcfc, 0xc000); + qtest_outl(s, 0xcf8, 0x80000804); + qtest_outw(s, 0xcfc, 0x05); + qtest_writeb(s, 0x69736c10, 0x08); + qtest_writeb(s, 0x69736c13, 0x58); + qtest_writeb(s, 0x69736c1a, 0x01); + qtest_writeb(s, 0x69736c1b, 0x06); + qtest_writeb(s, 0x69736c22, 0x01); + qtest_writeb(s, 0x69736c23, 0x07); + qtest_writeb(s, 0x69736c2b, 0x02); + qtest_writeb(s, 0x69736c48, 0x08); + qtest_writeb(s, 0x69736c4b, 0x58); + qtest_writeb(s, 0x69736c52, 0x04); + qtest_writeb(s, 0x69736c53, 0x06); + qtest_writeb(s, 0x69736c5b, 0x02); + qtest_outl(s, 0xc02d, 0x697300); + qtest_writeb(s, 0x5a554662, 0x01); + qtest_writeb(s, 0x5a554663, 0x07); + qtest_writeb(s, 0x5a55466a, 0x10); + qtest_writeb(s, 0x5a55466b, 0x22); + qtest_writeb(s, 0x5a55466c, 0x5a); + qtest_writeb(s, 0x5a55466d, 0x5a); + qtest_writeb(s, 0x5a55466e, 0x34); + qtest_writeb(s, 0x5a55466f, 0x5a); + qtest_writeb(s, 0x5a345a5a, 0x77); + qtest_writeb(s, 0x5a345a5b, 0x55); + qtest_writeb(s, 0x5a345a5c, 0x51); + qtest_writeb(s, 0x5a345a5d, 0x27); + qtest_writeb(s, 0x27515577, 0x41); + qtest_outl(s, 0xc02d, 0x5a5500); + qtest_writeb(s, 0x364001d0, 0x08); + qtest_writeb(s, 0x364001d3, 0x58); + qtest_writeb(s, 0x364001da, 0x01); + qtest_writeb(s, 0x364001db, 0x26); + qtest_writeb(s, 0x364001dc, 0x0d); + qtest_writeb(s, 0x364001dd, 0xae); + qtest_writeb(s, 0x364001de, 0x41); + qtest_writeb(s, 0x364001df, 0x5a); + qtest_writeb(s, 0x5a41ae0d, 0xf8); + qtest_writeb(s, 0x5a41ae0e, 0x36); + qtest_writeb(s, 0x5a41ae0f, 0xd7); + qtest_writeb(s, 0x5a41ae10, 0x36); + qtest_writeb(s, 0x36d736f8, 0x0c); + qtest_writeb(s, 0x36d736f9, 0x80); + qtest_writeb(s, 0x36d736fa, 0x0d); + qtest_outl(s, 0xc02d, 0x364000); + + qtest_quit(s); +} + /* * This used to trigger the assert in lsi_do_dma() * https://bugs.launchpad.net/qemu/+bug/697510 @@ -44,5 +117,8 @@ int main(int argc, char **argv) qtest_add_func("fuzz/lsi53c895a/lsi_do_dma_empty_queue", test_lsi_do_dma_empty_queue); + qtest_add_func("fuzz/lsi53c895a/lsi_do_msgout_cancel_req", + test_lsi_do_msgout_cancel_req); + return g_test_run(); }