Re: [Qemu-devel] [PATCH] tpm: fix alignment issues

[Stefan Berger]

On 01/29/2018 07:32 AM, Marc-André Lureau wrote:
> The new tpm-crb-test fails on sparc host:
>
> TEST: tests/tpm-crb-test... (pid=230409)
>    /i386/tpm-crb/test:
> Broken pipe
> FAIL
> GTester: last random seed: R02S29cea50247fe1efa59ee885a26d51a85
> (pid=230423)
> FAIL: tests/tpm-crb-test
>
> and generates a new clang sanitizer runtime warning:
>
> /home/petmay01/linaro/qemu-for-merges/hw/tpm/tpm_util.h:36:24: runtime
> error: load of misaligned address 0x7fdc24c00002 for type 'const
> uint32_t' (aka 'const unsigned int'), which requires 4 byte alignment
> 0x7fdc24c00002: note: pointer points here
> <memory cannot be printed>
>
> The sparc architecture does not allow misaligned loads and will
> segfault if you try them.  For example, this function:
>
> static inline uint32_t tpm_cmd_get_size(const void *b)
> {
>      return be32_to_cpu(*(const uint32_t *)(b + 2));
> }
>
> Should read,
>      return ldl_be_p(b + 2);
>
> As a general rule you can't take an arbitrary pointer into a byte
> buffer and try to interpret it as a structure or a pointer to a
> larger-than-bytesize-data simply by casting the pointer.
>
> Use this clean up as an opportunity to remove unnecessary temporary
> buffers and casts.
>
> Reported-by: Peter Maydell <address@hidden>
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
>   hw/tpm/tpm_util.h        | 17 ++++++++++-
>   hw/tpm/tpm_emulator.c    | 14 ++++-----
>   hw/tpm/tpm_passthrough.c |  6 ++--
>   hw/tpm/tpm_util.c        | 75 ++++++++++++++++++++++--------------------------
>   4 files changed, 58 insertions(+), 54 deletions(-)
>
> diff --git a/hw/tpm/tpm_util.h b/hw/tpm/tpm_util.h
> index 19b28474ae..c562140e52 100644
> --- a/hw/tpm/tpm_util.h
> +++ b/hw/tpm/tpm_util.h
> @@ -31,9 +31,24 @@ bool tpm_util_is_selftest(const uint8_t *in, uint32_t 
> in_len);
>
>   int tpm_util_test_tpmdev(int tpm_fd, TPMVersion *tpm_version);
>
> +static inline uint16_t tpm_cmd_get_tag(const void *b)
> +{
> +    return lduw_be_p(b);;
> +}
> +
>   static inline uint32_t tpm_cmd_get_size(const void *b)
>   {
> -    return be32_to_cpu(*(const uint32_t *)(b + 2));
> +    return ldl_be_p(b + 2);;

Why are there these two ';;' ?

> +}
> +
> +static inline uint32_t tpm_cmd_get_ordinal(const void *b)
> +{
> +    return ldl_be_p(b + 6);;
> +}
> +
> +static inline uint32_t tpm_cmd_get_errcode(const void *b)
> +{
> +    return ldl_be_p(b + 6);;
>   }
>
>   int tpm_util_get_buffer_size(int tpm_fd, TPMVersion tpm_version,
> diff --git a/hw/tpm/tpm_emulator.c b/hw/tpm/tpm_emulator.c
> index 35c78de5a9..a34a18ac7a 100644
> --- a/hw/tpm/tpm_emulator.c
> +++ b/hw/tpm/tpm_emulator.c
> @@ -120,7 +120,6 @@ static int tpm_emulator_unix_tx_bufs(TPMEmulator *tpm_emu,
>   {
>       ssize_t ret;
>       bool is_selftest = false;
> -    const struct tpm_resp_hdr *hdr = NULL;
>
>       if (selftest_done) {
>           *selftest_done = false;
> @@ -132,22 +131,21 @@ static int tpm_emulator_unix_tx_bufs(TPMEmulator *tpm_emu,
>           return -1;
>       }
>
> -    ret = qio_channel_read_all(tpm_emu->data_ioc, (char *)out, sizeof(*hdr),
> -                               err);
> +    ret = qio_channel_read_all(tpm_emu->data_ioc, (char *)out,
> +              sizeof(struct tpm_resp_hdr), err);
>       if (ret != 0) {
>           return -1;
>       }
>
> -    hdr = (struct tpm_resp_hdr *)out;
> -    out += sizeof(*hdr);
> -    ret = qio_channel_read_all(tpm_emu->data_ioc, (char *)out,
> -                               be32_to_cpu(hdr->len) - sizeof(*hdr) , err);
> +    ret = qio_channel_read_all(tpm_emu->data_ioc,
> +              (char *)out + sizeof(struct tpm_resp_hdr),
> +              tpm_cmd_get_size(out) - sizeof(struct tpm_resp_hdr), err);
>       if (ret != 0) {
>           return -1;
>       }
>
>       if (is_selftest) {
> -        *selftest_done = (be32_to_cpu(hdr->errcode) == 0);
> +        *selftest_done = tpm_cmd_get_errcode(out) == 0;
>       }
>
>       return 0;
> diff --git a/hw/tpm/tpm_passthrough.c b/hw/tpm/tpm_passthrough.c
> index 29142f38bb..537e11a3f9 100644
> --- a/hw/tpm/tpm_passthrough.c
> +++ b/hw/tpm/tpm_passthrough.c
> @@ -87,7 +87,6 @@ static int tpm_passthrough_unix_tx_bufs(TPMPassthruState 
> *tpm_pt,
>   {
>       ssize_t ret;
>       bool is_selftest;
> -    const struct tpm_resp_hdr *hdr;
>
>       /* FIXME: protect shared variables or use other sync mechanism */
>       tpm_pt->tpm_op_canceled = false;
> @@ -116,15 +115,14 @@ static int tpm_passthrough_unix_tx_bufs(TPMPassthruState 
> *tpm_pt,
>                            strerror(errno), errno);
>           }
>       } else if (ret < sizeof(struct tpm_resp_hdr) ||
> -               be32_to_cpu(((struct tpm_resp_hdr *)out)->len) != ret) {
> +               tpm_cmd_get_size(out) != ret) {
>           ret = -1;
>           error_report("tpm_passthrough: received invalid response "
>                        "packet from TPM");
>       }
>
>       if (is_selftest && (ret >= sizeof(struct tpm_resp_hdr))) {
> -        hdr = (struct tpm_resp_hdr *)out;
> -        *selftest_done = (be32_to_cpu(hdr->errcode) == 0);
> +        *selftest_done = tpm_cmd_get_errcode(out) == 0;
>       }
>
>   err_exit:
> diff --git a/hw/tpm/tpm_util.c b/hw/tpm/tpm_util.c
> index 747075e244..8abde59915 100644
> --- a/hw/tpm/tpm_util.c
> +++ b/hw/tpm/tpm_util.c
> @@ -106,20 +106,16 @@ const PropertyInfo qdev_prop_tpm = {
>   void tpm_util_write_fatal_error_response(uint8_t *out, uint32_t out_len)
>   {
>       if (out_len >= sizeof(struct tpm_resp_hdr)) {
> -        struct tpm_resp_hdr *resp = (struct tpm_resp_hdr *)out;
> -
> -        resp->tag = cpu_to_be16(TPM_TAG_RSP_COMMAND);
> -        resp->len = cpu_to_be32(sizeof(struct tpm_resp_hdr));
> -        resp->errcode = cpu_to_be32(TPM_FAIL);
> +        stw_be_p(out, TPM_TAG_RSP_COMMAND);
> +        stl_be_p(out + 2, sizeof(struct tpm_resp_hdr));
> +        stl_be_p(out + 6, TPM_FAIL);

Since we wrapped the getters we should wrap the setters as well. 
tpm_cmd_set_len(), tpm_cmd_set_errcode.

>       }
>   }
>
>   bool tpm_util_is_selftest(const uint8_t *in, uint32_t in_len)
>   {
> -    struct tpm_req_hdr *hdr = (struct tpm_req_hdr *)in;
> -
> -    if (in_len >= sizeof(*hdr)) {
> -        return (be32_to_cpu(hdr->ordinal) == TPM_ORD_ContinueSelfTest);
> +    if (in_len >= sizeof(struct tpm_req_hdr)) {
> +        return tpm_cmd_get_ordinal(in) == TPM_ORD_ContinueSelfTest;
>       }
>
>       return false;
> @@ -129,12 +125,11 @@ bool tpm_util_is_selftest(const uint8_t *in, uint32_t 
> in_len)
>    * Send request to a TPM device. We expect a response within one second.
>    */
>   static int tpm_util_request(int fd,
> -                            unsigned char *request,
> +                            const void *request,
>                               size_t requestlen,
> -                            unsigned char *response,
> +                            void *response,
>                               size_t responselen)
>   {
> -    struct tpm_resp_hdr *resp;
>       fd_set readfds;
>       int n;
>       struct timeval tv = {
> @@ -164,9 +159,8 @@ static int tpm_util_request(int fd,
>           return -EFAULT;
>       }
>
> -    resp = (struct tpm_resp_hdr *)response;
>       /* check the header */
> -    if (be32_to_cpu(resp->len) != n) {
> +    if (tpm_cmd_get_size(response) != n) {
>           return -EMSGSIZE;
>       }
>
> @@ -178,12 +172,11 @@ static int tpm_util_request(int fd,
>    * (error response is fine).
>    */
>   static int tpm_util_test(int fd,
> -                         unsigned char *request,
> +                         const void *request,
>                            size_t requestlen,
>                            uint16_t *return_tag)
>   {
> -    struct tpm_resp_hdr *resp;
> -    unsigned char buf[1024];
> +    char buf[1024];
>       ssize_t ret;
>
>       ret = tpm_util_request(fd, request, requestlen,
> @@ -192,8 +185,7 @@ static int tpm_util_test(int fd,
>           return ret;
>       }
>
> -    resp = (struct tpm_resp_hdr *)buf;
> -    *return_tag = be16_to_cpu(resp->tag);
> +    *return_tag = tpm_cmd_get_tag(buf);
>
>       return 0;
>   }
> @@ -228,7 +220,7 @@ int tpm_util_test_tpmdev(int tpm_fd, TPMVersion 
> *tpm_version)
>       int ret;
>
>       /* Send TPM 2 command */
> -    ret = tpm_util_test(tpm_fd, (unsigned char *)&test_req_tpm2,
> +    ret = tpm_util_test(tpm_fd, &test_req_tpm2,
>                           sizeof(test_req_tpm2), &return_tag);
>       /* TPM 2 would respond with a tag of TPM2_ST_NO_SESSIONS */
>       if (!ret && return_tag == TPM2_ST_NO_SESSIONS) {
> @@ -237,7 +229,7 @@ int tpm_util_test_tpmdev(int tpm_fd, TPMVersion 
> *tpm_version)
>       }
>
>       /* Send TPM 1.2 command */
> -    ret = tpm_util_test(tpm_fd, (unsigned char *)&test_req,
> +    ret = tpm_util_test(tpm_fd, &test_req,
>                           sizeof(test_req), &return_tag);
>       if (!ret && return_tag == TPM_TAG_RSP_COMMAND) {
>           *tpm_version = TPM_VERSION_1_2;
> @@ -253,7 +245,6 @@ int tpm_util_test_tpmdev(int tpm_fd, TPMVersion 
> *tpm_version)
>   int tpm_util_get_buffer_size(int tpm_fd, TPMVersion tpm_version,
>                                size_t *buffersize)
>   {
> -    unsigned char buf[1024];
>       int ret;
>
>       switch (tpm_version) {
> @@ -277,26 +268,27 @@ int tpm_util_get_buffer_size(int tpm_fd, TPMVersion 
> tpm_version,
>               struct tpm_resp_hdr hdr;
>               uint32_t len;
>               uint32_t buffersize;
> -        } QEMU_PACKED *tpm_resp = (struct tpm_resp_get_buffer_size *)buf;
> +        } QEMU_PACKED tpm_resp;
>
> -        ret = tpm_util_request(tpm_fd, (unsigned char *)&tpm_get_buffer_size,
> -                               sizeof(tpm_get_buffer_size), buf, sizeof(buf));
> +        ret = tpm_util_request(tpm_fd, &tpm_get_buffer_size,
> +                               sizeof(tpm_get_buffer_size),
> +                               &tpm_resp, sizeof(tpm_resp));
>           if (ret < 0) {
>               return ret;
>           }
>
> -        if (be32_to_cpu(tpm_resp->hdr.len) != sizeof(*tpm_resp) ||
> -            be32_to_cpu(tpm_resp->len) != sizeof(uint32_t)) {
> +        if (be32_to_cpu(tpm_resp.hdr.len) != sizeof(tpm_resp) ||
> +            be32_to_cpu(tpm_resp.len) != sizeof(uint32_t)) {
>               DPRINTF("tpm_resp->hdr.len = %u, expected = %zu\n",
> -                    be32_to_cpu(tpm_resp->hdr.len), sizeof(*tpm_resp));
> +                    be32_to_cpu(tpm_resp.hdr.len), sizeof(tpm_resp));
>               DPRINTF("tpm_resp->len = %u, expected = %zu\n",
> -                    be32_to_cpu(tpm_resp->len), sizeof(uint32_t));
> +                    be32_to_cpu(tpm_resp.len), sizeof(uint32_t));
>               error_report("tpm_util: Got unexpected response to "
>                            "TPM_GetCapability; errcode: 0x%x",
> -                         be32_to_cpu(tpm_resp->hdr.errcode));
> +                         be32_to_cpu(tpm_resp.hdr.errcode));
>               return -EFAULT;
>           }
> -        *buffersize = be32_to_cpu(tpm_resp->buffersize);
> +        *buffersize = be32_to_cpu(tpm_resp.buffersize);
>           break;
>       }
>       case TPM_VERSION_2_0: {
> @@ -324,27 +316,28 @@ int tpm_util_get_buffer_size(int tpm_fd, TPMVersion 
> tpm_version,
>               uint32_t value1;
>               uint32_t property2;
>               uint32_t value2;
> -        } QEMU_PACKED *tpm2_resp = (struct tpm2_resp_get_buffer_size *)buf;
> +        } QEMU_PACKED tpm2_resp;
>
> -        ret = tpm_util_request(tpm_fd, (unsigned char *)&tpm2_get_buffer_size,
> -                               sizeof(tpm2_get_buffer_size), buf, sizeof(buf));
> +        ret = tpm_util_request(tpm_fd, &tpm2_get_buffer_size,
> +                               sizeof(tpm2_get_buffer_size),
> +                               &tpm2_resp, sizeof(tpm2_resp));
>           if (ret < 0) {
>               return ret;
>           }
>
> -        if (be32_to_cpu(tpm2_resp->hdr.len) != sizeof(*tpm2_resp) ||
> -            be32_to_cpu(tpm2_resp->count) != 2) {
> +        if (be32_to_cpu(tpm2_resp.hdr.len) != sizeof(tpm2_resp) ||
> +            be32_to_cpu(tpm2_resp.count) != 2) {
>               DPRINTF("tpm2_resp->hdr.len = %u, expected = %zu\n",
> -                    be32_to_cpu(tpm2_resp->hdr.len), sizeof(*tpm2_resp));
> +                    be32_to_cpu(tpm2_resp.hdr.len), sizeof(tpm2_resp));
>               DPRINTF("tpm2_resp->len = %u, expected = %u\n",
> -                    be32_to_cpu(tpm2_resp->count), 2);
> +                    be32_to_cpu(tpm2_resp.count), 2);
>               error_report("tpm_util: Got unexpected response to "
>                            "TPM2_GetCapability; errcode: 0x%x",
> -                         be32_to_cpu(tpm2_resp->hdr.errcode));
> +                         be32_to_cpu(tpm2_resp.hdr.errcode));
>               return -EFAULT;
>           }
> -        *buffersize = MAX(be32_to_cpu(tpm2_resp->value1),
> -                          be32_to_cpu(tpm2_resp->value2));
> +        *buffersize = MAX(be32_to_cpu(tpm2_resp.value1),
> +                          be32_to_cpu(tpm2_resp.value2));
>           break;
>       }
>       case TPM_VERSION_UNSPEC: