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[Qemu-devel] [PATCH] net: fix misaligned member access

Marc-André Lureau posted 1 patch 6 years, 2 months ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20180209190340.19516-1-marcandre.lureau@redhat.com
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include/net/eth.h   | 4 +++-
hw/net/net_tx_pkt.c | 2 +-
2 files changed, 4 insertions(+), 2 deletions(-)
[Qemu-devel] [PATCH] net: fix misaligned member access
Posted by Marc-André Lureau 6 years, 2 months ago 
Fixes the following ASAN warnings:

/home/elmarco/src/qemu/hw/net/net_tx_pkt.c:201:27: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
0x631000028846: note: pointer points here
 01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
             ^
/home/elmarco/src/qemu/hw/net/net_tx_pkt.c:208:63: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
0x631000028846: note: pointer points here
 01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
             ^
/home/elmarco/src/qemu/hw/net/net_tx_pkt.c:210:13: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
0x631000028846: note: pointer points here
 01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 include/net/eth.h   | 4 +++-
 hw/net/net_tx_pkt.c | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/net/eth.h b/include/net/eth.h
index 09054a506d..e6dc8a7ba0 100644
--- a/include/net/eth.h
+++ b/include/net/eth.h
@@ -194,7 +194,9 @@ struct tcp_hdr {
 #define PKT_GET_IP_HDR(p)         \
     ((struct ip_header *)(((uint8_t *)(p)) + eth_get_l2_hdr_length(p)))
 #define IP_HDR_GET_LEN(p)         \
-    ((((struct ip_header *)(p))->ip_ver_len & 0x0F) << 2)
+    ((ldub_p(p + offsetof(struct ip_header, ip_ver_len)) & 0x0F) << 2)
+#define IP_HDR_GET_P(p)                                           \
+    (ldub_p(p + offsetof(struct ip_header, ip_p)))
 #define PKT_GET_IP_HDR_LEN(p)     \
     (IP_HDR_GET_LEN(PKT_GET_IP_HDR(p)))
 #define PKT_GET_IP6_HDR(p)        \
diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
index e29c881bc2..162f802dd7 100644
--- a/hw/net/net_tx_pkt.c
+++ b/hw/net/net_tx_pkt.c
@@ -205,7 +205,7 @@ static bool net_tx_pkt_parse_headers(struct NetTxPkt *pkt)
             return false;
         }
 
-        pkt->l4proto = ((struct ip_header *) l3_hdr->iov_base)->ip_p;
+        pkt->l4proto = IP_HDR_GET_P(l3_hdr->iov_base);
 
         if (IP_HDR_GET_LEN(l3_hdr->iov_base) != sizeof(struct ip_header)) {
             /* copy optional IPv4 header data if any*/
-- 
2.16.1.73.g5832b7e9f2
Re: [Qemu-devel] [PATCH] net: fix misaligned member access
Posted by Philippe Mathieu-Daudé 6 years, 2 months ago 
Hi Marc-André,

On 02/09/2018 04:03 PM, Marc-André Lureau wrote:
> Fixes the following ASAN warnings:
> 
> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:201:27: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
> 0x631000028846: note: pointer points here
>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>              ^
> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:208:63: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
> 0x631000028846: note: pointer points here
>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>              ^
> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:210:13: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
> 0x631000028846: note: pointer points here
>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/net/eth.h   | 4 +++-
>  hw/net/net_tx_pkt.c | 2 +-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/include/net/eth.h b/include/net/eth.h
> index 09054a506d..e6dc8a7ba0 100644
> --- a/include/net/eth.h
> +++ b/include/net/eth.h
> @@ -194,7 +194,9 @@ struct tcp_hdr {
>  #define PKT_GET_IP_HDR(p)         \
>      ((struct ip_header *)(((uint8_t *)(p)) + eth_get_l2_hdr_length(p)))
>  #define IP_HDR_GET_LEN(p)         \
> -    ((((struct ip_header *)(p))->ip_ver_len & 0x0F) << 2)
> +    ((ldub_p(p + offsetof(struct ip_header, ip_ver_len)) & 0x0F) << 2)

I like the idea of using the ldst API and offsetof() macro,
however I think it would be cleaner to use inlined static functions.

> +#define IP_HDR_GET_P(p)                                           \
> +    (ldub_p(p + offsetof(struct ip_header, ip_p)))
>  #define PKT_GET_IP_HDR_LEN(p)     \
>      (IP_HDR_GET_LEN(PKT_GET_IP_HDR(p)))
>  #define PKT_GET_IP6_HDR(p)        \
> diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
> index e29c881bc2..162f802dd7 100644
> --- a/hw/net/net_tx_pkt.c
> +++ b/hw/net/net_tx_pkt.c
> @@ -205,7 +205,7 @@ static bool net_tx_pkt_parse_headers(struct NetTxPkt *pkt)
>              return false;
>          }
>  
> -        pkt->l4proto = ((struct ip_header *) l3_hdr->iov_base)->ip_p;
> +        pkt->l4proto = IP_HDR_GET_P(l3_hdr->iov_base);
>  
>          if (IP_HDR_GET_LEN(l3_hdr->iov_base) != sizeof(struct ip_header)) {
>              /* copy optional IPv4 header data if any*/
>
Re: [Qemu-devel] [PATCH] net: fix misaligned member access
Posted by Marc-André Lureau 6 years, 2 months ago 
Hi

On Fri, Feb 9, 2018 at 8:50 PM, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> Hi Marc-André,
>
> On 02/09/2018 04:03 PM, Marc-André Lureau wrote:
>> Fixes the following ASAN warnings:
>>
>> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:201:27: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
>> 0x631000028846: note: pointer points here
>>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>>              ^
>> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:208:63: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
>> 0x631000028846: note: pointer points here
>>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>>              ^
>> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:210:13: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
>> 0x631000028846: note: pointer points here
>>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>>
>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
>> ---
>>  include/net/eth.h   | 4 +++-
>>  hw/net/net_tx_pkt.c | 2 +-
>>  2 files changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/net/eth.h b/include/net/eth.h
>> index 09054a506d..e6dc8a7ba0 100644
>> --- a/include/net/eth.h
>> +++ b/include/net/eth.h
>> @@ -194,7 +194,9 @@ struct tcp_hdr {
>>  #define PKT_GET_IP_HDR(p)         \
>>      ((struct ip_header *)(((uint8_t *)(p)) + eth_get_l2_hdr_length(p)))
>>  #define IP_HDR_GET_LEN(p)         \
>> -    ((((struct ip_header *)(p))->ip_ver_len & 0x0F) << 2)
>> +    ((ldub_p(p + offsetof(struct ip_header, ip_ver_len)) & 0x0F) << 2)
>
> I like the idea of using the ldst API and offsetof() macro,
> however I think it would be cleaner to use inlined static functions.

Could be a different patch. I don't see much reason to mix this with
the alignment fix.

Then you need to review the rest of the define too.

Thanks

>
>> +#define IP_HDR_GET_P(p)                                           \
>> +    (ldub_p(p + offsetof(struct ip_header, ip_p)))
>>  #define PKT_GET_IP_HDR_LEN(p)     \
>>      (IP_HDR_GET_LEN(PKT_GET_IP_HDR(p)))
>>  #define PKT_GET_IP6_HDR(p)        \
>> diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
>> index e29c881bc2..162f802dd7 100644
>> --- a/hw/net/net_tx_pkt.c
>> +++ b/hw/net/net_tx_pkt.c
>> @@ -205,7 +205,7 @@ static bool net_tx_pkt_parse_headers(struct NetTxPkt *pkt)
>>              return false;
>>          }
>>
>> -        pkt->l4proto = ((struct ip_header *) l3_hdr->iov_base)->ip_p;
>> +        pkt->l4proto = IP_HDR_GET_P(l3_hdr->iov_base);
>>
>>          if (IP_HDR_GET_LEN(l3_hdr->iov_base) != sizeof(struct ip_header)) {
>>              /* copy optional IPv4 header data if any*/
>>
>



-- 
Marc-André Lureau
Re: [Qemu-devel] [PATCH] net: fix misaligned member access
Posted by Peter Maydell 6 years, 1 month ago 
On 9 February 2018 at 19:03, Marc-André Lureau
<marcandre.lureau@redhat.com> wrote:
> Fixes the following ASAN warnings:
>
> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:201:27: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
> 0x631000028846: note: pointer points here
>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>              ^
> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:208:63: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
> 0x631000028846: note: pointer points here
>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>              ^
> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:210:13: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
> 0x631000028846: note: pointer points here
>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/net/eth.h   | 4 +++-
>  hw/net/net_tx_pkt.c | 2 +-
>  2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/eth.h b/include/net/eth.h
> index 09054a506d..e6dc8a7ba0 100644
> --- a/include/net/eth.h
> +++ b/include/net/eth.h
> @@ -194,7 +194,9 @@ struct tcp_hdr {
>  #define PKT_GET_IP_HDR(p)         \
>      ((struct ip_header *)(((uint8_t *)(p)) + eth_get_l2_hdr_length(p)))
>  #define IP_HDR_GET_LEN(p)         \
> -    ((((struct ip_header *)(p))->ip_ver_len & 0x0F) << 2)
> +    ((ldub_p(p + offsetof(struct ip_header, ip_ver_len)) & 0x0F) << 2)
> +#define IP_HDR_GET_P(p)                                           \
> +    (ldub_p(p + offsetof(struct ip_header, ip_p)))
>  #define PKT_GET_IP_HDR_LEN(p)     \
>      (IP_HDR_GET_LEN(PKT_GET_IP_HDR(p)))
>  #define PKT_GET_IP6_HDR(p)        \
> diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
> index e29c881bc2..162f802dd7 100644
> --- a/hw/net/net_tx_pkt.c
> +++ b/hw/net/net_tx_pkt.c
> @@ -205,7 +205,7 @@ static bool net_tx_pkt_parse_headers(struct NetTxPkt *pkt)
>              return false;
>          }
>
> -        pkt->l4proto = ((struct ip_header *) l3_hdr->iov_base)->ip_p;
> +        pkt->l4proto = IP_HDR_GET_P(l3_hdr->iov_base);
>
>          if (IP_HDR_GET_LEN(l3_hdr->iov_base) != sizeof(struct ip_header)) {
>              /* copy optional IPv4 header data if any*/
> --
> 2.16.1.73.g5832b7e9f2

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

and I'm going to apply this to master, because I'm fed up of the warnings
in my build system logs.

It looks like all these macros need to be fixed, though, not just these two.

thanks
-- PMM
Re: [Qemu-devel] [PATCH] net: fix misaligned member access
Posted by Peter Maydell 6 years, 1 month ago 
On 2 March 2018 at 17:22, Peter Maydell <peter.maydell@linaro.org> wrote:
> On 9 February 2018 at 19:03, Marc-André Lureau
> <marcandre.lureau@redhat.com> wrote:
>> Fixes the following ASAN warnings:
>>
>> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:201:27: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
>> 0x631000028846: note: pointer points here
>>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>>              ^
>> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:208:63: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
>> 0x631000028846: note: pointer points here
>>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>>              ^
>> /home/elmarco/src/qemu/hw/net/net_tx_pkt.c:210:13: runtime error: member access within misaligned address 0x631000028846 for type 'struct ip_header', which requires 4 byte alignment
>> 0x631000028846: note: pointer points here
>>  01 00 00 00 45 00  01 a9 01 00 00 00 40 11  78 45 00 00 00 00 ff ff  ff ff 00 00 00 00 00 00  00 00
>>
>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
>> ---
>>  include/net/eth.h   | 4 +++-
>>  hw/net/net_tx_pkt.c | 2 +-
>>  2 files changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/net/eth.h b/include/net/eth.h
>> index 09054a506d..e6dc8a7ba0 100644
>> --- a/include/net/eth.h
>> +++ b/include/net/eth.h
>> @@ -194,7 +194,9 @@ struct tcp_hdr {
>>  #define PKT_GET_IP_HDR(p)         \
>>      ((struct ip_header *)(((uint8_t *)(p)) + eth_get_l2_hdr_length(p)))
>>  #define IP_HDR_GET_LEN(p)         \
>> -    ((((struct ip_header *)(p))->ip_ver_len & 0x0F) << 2)
>> +    ((ldub_p(p + offsetof(struct ip_header, ip_ver_len)) & 0x0F) << 2)
>> +#define IP_HDR_GET_P(p)                                           \
>> +    (ldub_p(p + offsetof(struct ip_header, ip_p)))
>>  #define PKT_GET_IP_HDR_LEN(p)     \
>>      (IP_HDR_GET_LEN(PKT_GET_IP_HDR(p)))
>>  #define PKT_GET_IP6_HDR(p)        \
>> diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
>> index e29c881bc2..162f802dd7 100644
>> --- a/hw/net/net_tx_pkt.c
>> +++ b/hw/net/net_tx_pkt.c
>> @@ -205,7 +205,7 @@ static bool net_tx_pkt_parse_headers(struct NetTxPkt *pkt)
>>              return false;
>>          }
>>
>> -        pkt->l4proto = ((struct ip_header *) l3_hdr->iov_base)->ip_p;
>> +        pkt->l4proto = IP_HDR_GET_P(l3_hdr->iov_base);
>>
>>          if (IP_HDR_GET_LEN(l3_hdr->iov_base) != sizeof(struct ip_header)) {
>>              /* copy optional IPv4 header data if any*/
>> --
>> 2.16.1.73.g5832b7e9f2
>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
>
> and I'm going to apply this to master, because I'm fed up of the warnings
> in my build system logs.

Now applied to master, thanks.

-- PMM

Patchew 2.1-devel-0870f84

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