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[PATCH 97/97] scsi: lsi: exit infinite loop while executing script (CVE-
From: |
Michael Roth |
Subject: |
[PATCH 97/97] scsi: lsi: exit infinite loop while executing script (CVE-2019-12068) |
Date: |
Tue, 1 Oct 2019 18:46:16 -0500 |
From: Paolo Bonzini <address@hidden>
When executing script in lsi_execute_script(), the LSI scsi adapter
emulator advances 's->dsp' index to read next opcode. This can lead
to an infinite loop if the next opcode is empty. Move the existing
loop exit after 10k iterations so that it covers no-op opcodes as
well.
Reported-by: Bugs SysSec <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
Signed-off-by: Prasad J Pandit <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
(cherry picked from commit de594e47659029316bbf9391efb79da0a1a08e08)
Signed-off-by: Michael Roth <address@hidden>
---
hw/scsi/lsi53c895a.c | 41 +++++++++++++++++++++++++++--------------
1 file changed, 27 insertions(+), 14 deletions(-)
diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
index da7239d94f..d3380b6f95 100644
--- a/hw/scsi/lsi53c895a.c
+++ b/hw/scsi/lsi53c895a.c
@@ -184,6 +184,9 @@ static const char *names[] = {
/* Flag set if this is a tagged command. */
#define LSI_TAG_VALID (1 << 16)
+/* Maximum instructions to process. */
+#define LSI_MAX_INSN 10000
+
typedef struct lsi_request {
SCSIRequest *req;
uint32_t tag;
@@ -1131,7 +1134,21 @@ static void lsi_execute_script(LSIState *s)
s->istat1 |= LSI_ISTAT1_SRUN;
again:
- insn_processed++;
+ if (++insn_processed > LSI_MAX_INSN) {
+ /* Some windows drivers make the device spin waiting for a memory
+ location to change. If we have been executed a lot of code then
+ assume this is the case and force an unexpected device disconnect.
+ This is apparently sufficient to beat the drivers into submission.
+ */
+ if (!(s->sien0 & LSI_SIST0_UDC)) {
+ qemu_log_mask(LOG_GUEST_ERROR,
+ "lsi_scsi: inf. loop with UDC masked");
+ }
+ lsi_script_scsi_interrupt(s, LSI_SIST0_UDC, 0);
+ lsi_disconnect(s);
+ trace_lsi_execute_script_stop();
+ return;
+ }
insn = read_dword(s, s->dsp);
if (!insn) {
/* If we receive an empty opcode increment the DSP by 4 bytes
@@ -1568,19 +1585,7 @@ again:
}
}
}
- if (insn_processed > 10000 && s->waiting == LSI_NOWAIT) {
- /* Some windows drivers make the device spin waiting for a memory
- location to change. If we have been executed a lot of code then
- assume this is the case and force an unexpected device disconnect.
- This is apparently sufficient to beat the drivers into submission.
- */
- if (!(s->sien0 & LSI_SIST0_UDC)) {
- qemu_log_mask(LOG_GUEST_ERROR,
- "lsi_scsi: inf. loop with UDC masked");
- }
- lsi_script_scsi_interrupt(s, LSI_SIST0_UDC, 0);
- lsi_disconnect(s);
- } else if (s->istat1 & LSI_ISTAT1_SRUN && s->waiting == LSI_NOWAIT) {
+ if (s->istat1 & LSI_ISTAT1_SRUN && s->waiting == LSI_NOWAIT) {
if (s->dcntl & LSI_DCNTL_SSM) {
lsi_script_dma_interrupt(s, LSI_DSTAT_SSI);
} else {
@@ -1968,6 +1973,10 @@ static void lsi_reg_writeb(LSIState *s, int offset,
uint8_t val)
case 0x2f: /* DSP[24:31] */
s->dsp &= 0x00ffffff;
s->dsp |= val << 24;
+ /*
+ * FIXME: if s->waiting != LSI_NOWAIT, this will only execute one
+ * instruction. Is this correct?
+ */
if ((s->dmode & LSI_DMODE_MAN) == 0
&& (s->istat1 & LSI_ISTAT1_SRUN) == 0)
lsi_execute_script(s);
@@ -1986,6 +1995,10 @@ static void lsi_reg_writeb(LSIState *s, int offset,
uint8_t val)
break;
case 0x3b: /* DCNTL */
s->dcntl = val & ~(LSI_DCNTL_PFF | LSI_DCNTL_STD);
+ /*
+ * FIXME: if s->waiting != LSI_NOWAIT, this will only execute one
+ * instruction. Is this correct?
+ */
if ((val & LSI_DCNTL_STD) && (s->istat1 & LSI_ISTAT1_SRUN) == 0)
lsi_execute_script(s);
break;
--
2.17.1
- [PATCH 73/97] target/arm: Don't abort on M-profile exception return in linux-user mode, (continued)
- [PATCH 73/97] target/arm: Don't abort on M-profile exception return in linux-user mode, Michael Roth, 2019/10/01
- [PATCH 84/97] block/nfs: tear down aio before nfs_close, Michael Roth, 2019/10/01
- [PATCH 92/97] curl: Check curl_multi_add_handle()'s return code, Michael Roth, 2019/10/01
- [PATCH 10/97] spapr/xive: fix EQ page addresses above 64GB, Michael Roth, 2019/10/01
- [PATCH 06/97] block: Fix AioContext switch for bs->drv == NULL, Michael Roth, 2019/10/01
- [PATCH 96/97] hw/core/loader: Fix possible crash in rom_copy(), Michael Roth, 2019/10/01
- [PATCH 93/97] slirp: Fix heap overflow in ip_reass on big packet input, Michael Roth, 2019/10/01
- [PATCH 95/97] s390: PCI: fix IOMMU region init, Michael Roth, 2019/10/01
- [PATCH 63/97] backup: Copy only dirty areas, Michael Roth, 2019/10/01
- [PATCH 08/97] Makefile: add nit-picky mode to sphinx-build, Michael Roth, 2019/10/01
- [PATCH 97/97] scsi: lsi: exit infinite loop while executing script (CVE-2019-12068),
Michael Roth <=
- [PATCH 74/97] xen-bus: Fix backend state transition on device reset, Michael Roth, 2019/10/01
- [PATCH 75/97] pr-manager: Fix invalid g_free() crash bug, Michael Roth, 2019/10/01
- [PATCH 94/97] slirp: ip_reass: Fix use after free, Michael Roth, 2019/10/01
- [PATCH 09/97] docs/interop/bitmaps: rewrite and modernize doc, Michael Roth, 2019/10/01
- [PATCH 23/97] iotests: add iotest 256 for testing blockdev-backup across iothread contexts, Michael Roth, 2019/10/01
- [PATCH 91/97] curl: Handle success in multi_check_completion, Michael Roth, 2019/10/01
- [PATCH 19/97] iotests.py: do not use infinite waits, Michael Roth, 2019/10/01
- Re: [PATCH 00/97] Patch Round-up for stable 4.0.1, freeze on 2019-10-10, Thomas Huth, 2019/10/02
- Re: [PATCH 00/97] Patch Round-up for stable 4.0.1, freeze on 2019-10-10, Philippe Mathieu-Daudé, 2019/10/03