UBSAN: support __ubsan_handle_type_mismatch_v1

Message ID 20180208154636.21320-1-mark.rutland@arm.com
State New
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  • UBSAN: support __ubsan_handle_type_mismatch_v1
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Commit Message

Mark Rutland Feb. 8, 2018, 3:46 p.m.
Originally, UBSAN's __ubsan_handle_type_mismatch took a struct
type_mismatch_data, as defined in lib/ubsan.h. This has an unsigned long
alignment field.

New versions of UBSAN call __ubsan_handle_type_mismatch_v1, which is
similar to __ubsan_handle_type_mismatch, but takes a different struct
where the alignment is stored in an unsigned char (as log2 of the
alignment). All other fields are unchanged.

As we don't implement __ubsan_handle_type_mismatch_v1, the kernel will
fail to link when compiled with compilers using the new ABI (e.g. clang
form the LLVM 5.0.0 release).

This patch adds support for the new ABI. To keep things simple, we
simply convert the new data format into the old format, and hand it on
to the existing handlers.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
 lib/ubsan.c | 14 ++++++++++++++
 lib/ubsan.h |  7 +++++++
 2 files changed, 21 insertions(+)

Andrey, does this look correct to you? Are there any other new ABI bits
that need to be plumbed in?

Mark.

-- 
2.11.0

Comments

Andrey Ryabinin Feb. 8, 2018, 4:05 p.m. | #1
On 02/08/2018 06:46 PM, Mark Rutland wrote:
> Originally, UBSAN's __ubsan_handle_type_mismatch took a struct

> type_mismatch_data, as defined in lib/ubsan.h. This has an unsigned long

> alignment field.

> 

> New versions of UBSAN call __ubsan_handle_type_mismatch_v1, which is

> similar to __ubsan_handle_type_mismatch, but takes a different struct

> where the alignment is stored in an unsigned char (as log2 of the

> alignment). All other fields are unchanged.

> 

> As we don't implement __ubsan_handle_type_mismatch_v1, the kernel will

> fail to link when compiled with compilers using the new ABI (e.g. clang

> form the LLVM 5.0.0 release).

> 

> This patch adds support for the new ABI. To keep things simple, we

> simply convert the new data format into the old format, and hand it on

> to the existing handlers.

> 

> Signed-off-by: Mark Rutland <mark.rutland@arm.com>

> Cc: Andrew Morton <akpm@linux-foundation.org>

> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>

> ---

>  lib/ubsan.c | 14 ++++++++++++++

>  lib/ubsan.h |  7 +++++++

>  2 files changed, 21 insertions(+)

> 

> Andrey, does this look correct to you?


Almost.
Commit 42440c1f9911b4b7b8ba3dc4e90c1197bc561211 looks correct to me ;)

Copying ->location is wrong, because we use bit in location struct to suppress multiple
reports of the same location, see was_reported(). So in you case REPORTED_BIT will be set
on stack and original source_location remain unchanged.


> Are there any other new ABI bits that need to be plumbed in?

> 


ABI of __ubsan_handle_nonnull_return() changed as well, but it's never used in the kernel
and probably never will be. Thus I removed it, see bac7a1fff7926fb9891a18fe33650884b0e13e4
Mark Rutland Feb. 8, 2018, 4:16 p.m. | #2
On Thu, Feb 08, 2018 at 07:05:14PM +0300, Andrey Ryabinin wrote:
> On 02/08/2018 06:46 PM, Mark Rutland wrote:

> > Originally, UBSAN's __ubsan_handle_type_mismatch took a struct

> > type_mismatch_data, as defined in lib/ubsan.h. This has an unsigned long

> > alignment field.

> > 

> > New versions of UBSAN call __ubsan_handle_type_mismatch_v1, which is

> > similar to __ubsan_handle_type_mismatch, but takes a different struct

> > where the alignment is stored in an unsigned char (as log2 of the

> > alignment). All other fields are unchanged.

> > 

> > As we don't implement __ubsan_handle_type_mismatch_v1, the kernel will

> > fail to link when compiled with compilers using the new ABI (e.g. clang

> > form the LLVM 5.0.0 release).

> > 

> > This patch adds support for the new ABI. To keep things simple, we

> > simply convert the new data format into the old format, and hand it on

> > to the existing handlers.

> > 

> > Signed-off-by: Mark Rutland <mark.rutland@arm.com>

> > Cc: Andrew Morton <akpm@linux-foundation.org>

> > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>

> > ---

> >  lib/ubsan.c | 14 ++++++++++++++

> >  lib/ubsan.h |  7 +++++++

> >  2 files changed, 21 insertions(+)

> > 

> > Andrey, does this look correct to you?

> 

> Almost.

> Commit 42440c1f9911b4b7b8ba3dc4e90c1197bc561211 looks correct to me ;)


Ah, I didn't spot something had already been queued. Sorry for the
noise, and thanks for implementing this!

> Copying ->location is wrong, because we use bit in location struct to suppress multiple

> reports of the same location, see was_reported(). So in you case REPORTED_BIT will be set

> on stack and original source_location remain unchanged.

>

> > Are there any other new ABI bits that need to be plumbed in?

> 

> ABI of __ubsan_handle_nonnull_return() changed as well, but it's never used in the kernel

> and probably never will be. Thus I removed it, see bac7a1fff7926fb9891a18fe33650884b0e13e4


Noted.

I'll cherry-pick these into my local testing branch while I await
v4.16-rc1.

Mark.

Patch

diff --git a/lib/ubsan.c b/lib/ubsan.c
index fb0409df1bcf..b7af7d3478a9 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -328,6 +328,20 @@  void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
 }
 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
 
+void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data_v1,
+				     unsigned long ptr)
+{
+	struct type_mismatch_data data = {
+		.location = data_v1->location,
+		.type = data_v1->type,
+		.alignment = 1UL << data_v1->log_alignment,
+		.type_check_kind = data_v1->type_check_kind,
+	};
+
+	__ubsan_handle_type_mismatch(&data, ptr);
+}
+EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
+
 void __ubsan_handle_nonnull_return(struct nonnull_return_data *data)
 {
 	unsigned long flags;
diff --git a/lib/ubsan.h b/lib/ubsan.h
index 88f23557edbe..dc0b8cbc7f57 100644
--- a/lib/ubsan.h
+++ b/lib/ubsan.h
@@ -37,6 +37,13 @@  struct type_mismatch_data {
 	unsigned char type_check_kind;
 };
 
+struct type_mismatch_data_v1 {
+	struct source_location location;
+	struct type_descriptor *type;
+	unsigned char log_alignment;
+	unsigned char type_check_kind;
+};
+
 struct nonnull_arg_data {
 	struct source_location location;
 	struct source_location attr_location;