On 11/20/18 2:22 AM, P J P wrote:
From: Prasad J Pandit <p...@fedoraproject.org>
While performing mmio device r/w operations, guest could set 'addr'
parameter such that 'locty' index exceeds TPM_TIS_NUM_LOCALITIES=5
after setting new 'locty' via 'tpm_tis_new_active_locality'.
Add check to avoid OOB access.
Do you have test code that can set the memory to such a locality or is
this purely hypothetical at the moment?
We are registering this MMIO area:
memory_region_init_io(&s->mmio, OBJECT(s), &tpm_tis_memory_ops,
s, "tpm-tis-mmio",
TPM_TIS_NUM_LOCALITIES <<
TPM_TIS_LOCALITY_SHIFT);
#define TPM_TIS_NUM_LOCALITIES 5
#define TPM_TIS_LOCALITY_SHIFT 12
--> 5 << 12 = 0x5000, thus we get memory locations [0 .. 0x4fff]
We have the following code to get from an address to the locality:
static uint8_t tpm_tis_locality_from_addr(hwaddr addr)
{
return (uint8_t)((addr >> TPM_TIS_LOCALITY_SHIFT) & 0x7);
}
With this we would get localities of [0x0 .. 0x4] following the memory
locations [0 .. 0x4fff] above.
Stefan
Reported-by: Cheng Feng <ps...@huawei.com>
Signed-off-by: Prasad J Pandit <p...@fedoraproject.org>
---
hw/tpm/tpm_tis.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
Update: add assert() calls
-> https://lists.gnu.org/archive/html/qemu-devel/2018-11/msg00912.html
diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
index 12f5c9a759..d6bf3ceb26 100644
--- a/hw/tpm/tpm_tis.c
+++ b/hw/tpm/tpm_tis.c
@@ -293,6 +293,7 @@ static void tpm_tis_request_completed(TPMIf *ti, int ret)
uint8_t locty = s->cmd.locty;
uint8_t l;
+ assert(TPM_TIS_IS_VALID_LOCTY(locty));
if (s->cmd.selftest_done) {
for (l = 0; l < TPM_TIS_NUM_LOCALITIES; l++) {
s->loc[locty].sts |= TPM_TIS_STS_SELFTEST_DONE;
@@ -401,6 +402,7 @@ static uint64_t tpm_tis_mmio_read(void *opaque, hwaddr addr,
uint32_t avail;
uint8_t v;
+ assert(TPM_TIS_IS_VALID_LOCTY(locty));
if (tpm_backend_had_startup_error(s->be_driver)) {
return 0;
}
@@ -523,6 +525,7 @@ static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
uint16_t len;
uint32_t mask = (size == 1) ? 0xff : ((size == 2) ? 0xffff : ~0);
+ assert(TPM_TIS_IS_VALID_LOCTY(locty));
trace_tpm_tis_mmio_write(size, addr, val);
if (locty == 4) {
@@ -642,7 +645,7 @@ static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
}
}
- if (set_new_locty) {
+ if (set_new_locty && TPM_TIS_IS_VALID_LOCTY(active_locty)) {
tpm_tis_new_active_locality(s, active_locty);
}
