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scsi/lsi53c895a: really fix use-after-free in lsi_do_msgout (CVE-2022-0216)

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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 <mcascell@redhat.com>
Tested-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20220711123316.421279-1-mcascell@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Mauro Matteo Cascella 2022-07-11 14:33:16 +02:00 committed by Paolo Bonzini
parent 8e3d85d36b
commit 4367a20cc4
2 changed files with 78 additions and 1 deletions
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3
hw/scsi/lsi53c895a.c
View file

@ -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

76
tests/qtest/fuzz-lsi53c895a-test.c
View file

@ -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();
}