Hi Andrew:
Sorry for the mistaken of the Andrey's email.
After the test I found this version still exist the problem that will transfer
the align problem to size
mismatch, I will send a new version to fix it.
The correct way is like this:
diff --git a/lib/ubsan.c b/lib/ubsan.c
index fb0409d..0799678 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -321,9 +321,10 @@ void __ubsan_handle_type_mismatch(struct
type_mismatch_data *data,
if (!ptr)
handle_null_ptr_deref(data);
- else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
- handle_missaligned_access(data, ptr);
- else
+ else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) {
+ if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
+ handle_missaligned_access(data, ptr);
+ } else
handle_object_size_mismatch(data, ptr);
}
EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
--
Thanks
Ding
On 2017/12/7 8:49, Andrew Morton wrote:
> (correcting Andrey's email address)
>
>
> From: Ding Tianhong <[email protected]>
> Subject: lib/ubsan.c: don't handle misaligned address when kernel supports
> unaligned access
>
> ubsan reports a warning like:
>
> UBSAN: Undefined behaviour in ../include/linux/etherdevice.h:386:9
> load of misaligned address ffffffc069ba0482 for type 'long unsigned int'
> which requires 8 byte alignment
> CPU: 0 PID: 901 Comm: sshd Not tainted 4.xx+ #1
> Hardware name: linux,dummy-virt (DT)
> Call trace:
> [<ffffffc000093600>] dump_backtrace+0x0/0x348
> [<ffffffc000093968>] show_stack+0x20/0x30
> [<ffffffc001651664>] dump_stack+0x144/0x1b4
> [<ffffffc0016519b0>] ubsan_epilogue+0x18/0x74
> [<ffffffc001651bac>] __ubsan_handle_type_mismatch+0x1a0/0x25c
> [<ffffffc00125d8a0>] dev_gro_receive+0x17d8/0x1830
> [<ffffffc00125d928>] napi_gro_receive+0x30/0x158
> [<ffffffc000f4f93c>] virtnet_receive+0xad4/0x1fa8
>
> The reason is that when enabling the CONFIG_UBSAN_ALIGNMENT, ubsan will
> report the unaligned access even if the system supports it
> (CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y). This produces a lot of noise
> in the log and causes confusion.
>
> Prevent the detection of unaligned access when the system support
> unaligned access.
>
> Link: http://lkml.kernel.org/r/[email protected]
> Signed-off-by: Ding Tianhong <[email protected]>
> Cc: David Laight <[email protected]>
> Cc: Andrey Ryabinin <[email protected]>
> Signed-off-by: Andrew Morton <[email protected]>
> ---
>
> lib/ubsan.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff -puN
> lib/ubsan.c~ubsan-dont-handle-misaligned-address-when-support-unaligned-access
> lib/ubsan.c
> ---
> a/lib/ubsan.c~ubsan-dont-handle-misaligned-address-when-support-unaligned-access
> +++ a/lib/ubsan.c
> @@ -322,7 +322,8 @@ void __ubsan_handle_type_mismatch(struct
> if (!ptr)
> handle_null_ptr_deref(data);
> else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
> - handle_missaligned_access(data, ptr);
> + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
> + handle_missaligned_access(data, ptr);
> else
> handle_object_size_mismatch(data, ptr);
> }
> _
>
>
> .
>
