* [PATCH v2 0/2] kasan: fixes for 5.11-rc
@ 2021-01-14 19:33 Andrey Konovalov
2021-01-14 19:33 ` [PATCH v2 1/2] kasan, mm: fix conflicts with init_on_alloc/free Andrey Konovalov
2021-01-14 19:33 ` [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports Andrey Konovalov
0 siblings, 2 replies; 5+ messages in thread
From: Andrey Konovalov @ 2021-01-14 19:33 UTC (permalink / raw)
To: Andrew Morton, Catalin Marinas, Vincenzo Frascino, Dmitry Vyukov,
Alexander Potapenko, Marco Elver
Cc: Branislav Rankov, Andrey Konovalov, Kevin Brodsky, Will Deacon,
linux-kernel, kasan-dev, linux-mm, linux-arm-kernel,
Andrey Ryabinin, Peter Collingbourne, Evgenii Stepanov
Changes v1->v2:
- Update changelog of patch #1.
Andrey Konovalov (2):
kasan, mm: fix conflicts with init_on_alloc/free
kasan, arm64: fix pointer tags in KASAN reports
arch/arm64/mm/fault.c | 2 ++
mm/slub.c | 7 ++++---
2 files changed, 6 insertions(+), 3 deletions(-)
--
2.30.0.284.gd98b1dd5eaa7-goog
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^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2 1/2] kasan, mm: fix conflicts with init_on_alloc/free
2021-01-14 19:33 [PATCH v2 0/2] kasan: fixes for 5.11-rc Andrey Konovalov
@ 2021-01-14 19:33 ` Andrey Konovalov
2021-01-14 19:33 ` [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports Andrey Konovalov
1 sibling, 0 replies; 5+ messages in thread
From: Andrey Konovalov @ 2021-01-14 19:33 UTC (permalink / raw)
To: Andrew Morton, Catalin Marinas, Vincenzo Frascino, Dmitry Vyukov,
Alexander Potapenko, Marco Elver
Cc: Branislav Rankov, Vlastimil Babka, Andrey Konovalov,
Kevin Brodsky, Will Deacon, linux-kernel, kasan-dev, linux-mm,
linux-arm-kernel, Andrey Ryabinin, Peter Collingbourne,
Evgenii Stepanov
A few places where SLUB accesses object's data or metadata were missed in
a previous patch. This leads to false positives with hardware tag-based
KASAN when bulk allocations are used with init_on_alloc/free.
Fix the false-positives by resetting pointer tags during these accesses.
(The kasan_reset_tag call is removed from slab_alloc_node, as it's added
into maybe_wipe_obj_freeptr.)
Link: https://linux-review.googlesource.com/id/I50dd32838a666e173fe06c3c5c766f2c36aae901
Fixes: aa1ef4d7b3f67 ("kasan, mm: reset tags when accessing metadata")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
mm/slub.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index dc5b42e700b8..75fb097d990d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2791,7 +2791,8 @@ static __always_inline void maybe_wipe_obj_freeptr(struct kmem_cache *s,
void *obj)
{
if (unlikely(slab_want_init_on_free(s)) && obj)
- memset((void *)((char *)obj + s->offset), 0, sizeof(void *));
+ memset((void *)((char *)kasan_reset_tag(obj) + s->offset),
+ 0, sizeof(void *));
}
/*
@@ -2883,7 +2884,7 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s,
stat(s, ALLOC_FASTPATH);
}
- maybe_wipe_obj_freeptr(s, kasan_reset_tag(object));
+ maybe_wipe_obj_freeptr(s, object);
if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object)
memset(kasan_reset_tag(object), 0, s->object_size);
@@ -3329,7 +3330,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
int j;
for (j = 0; j < i; j++)
- memset(p[j], 0, s->object_size);
+ memset(kasan_reset_tag(p[j]), 0, s->object_size);
}
/* memcg and kmem_cache debug support */
--
2.30.0.284.gd98b1dd5eaa7-goog
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^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports
2021-01-14 19:33 [PATCH v2 0/2] kasan: fixes for 5.11-rc Andrey Konovalov
2021-01-14 19:33 ` [PATCH v2 1/2] kasan, mm: fix conflicts with init_on_alloc/free Andrey Konovalov
@ 2021-01-14 19:33 ` Andrey Konovalov
2021-01-15 10:49 ` Catalin Marinas
1 sibling, 1 reply; 5+ messages in thread
From: Andrey Konovalov @ 2021-01-14 19:33 UTC (permalink / raw)
To: Andrew Morton, Catalin Marinas, Vincenzo Frascino, Dmitry Vyukov,
Alexander Potapenko, Marco Elver
Cc: Branislav Rankov, Andrey Konovalov, Kevin Brodsky, Will Deacon,
linux-kernel, kasan-dev, linux-mm, linux-arm-kernel,
Andrey Ryabinin, Peter Collingbourne, Evgenii Stepanov
As of the "arm64: expose FAR_EL1 tag bits in siginfo" patch, the address
that is passed to report_tag_fault has pointer tags in the format of 0x0X,
while KASAN uses 0xFX format (note the difference in the top 4 bits).
Fix up the pointer tag before calling kasan_report.
Link: https://linux-review.googlesource.com/id/I9ced973866036d8679e8f4ae325de547eb969649
Fixes: dceec3ff7807 ("arm64: expose FAR_EL1 tag bits in siginfo")
Fixes: 4291e9ee6189 ("kasan, arm64: print report from tag fault handler")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
arch/arm64/mm/fault.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 3c40da479899..a218f6f2fdc8 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -304,6 +304,8 @@ static void report_tag_fault(unsigned long addr, unsigned int esr,
{
bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
+ /* The format of KASAN tags is 0xF<x>. */
+ addr |= (0xF0UL << MTE_TAG_SHIFT);
/*
* SAS bits aren't set for all faults reported in EL1, so we can't
* find out access size.
--
2.30.0.284.gd98b1dd5eaa7-goog
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^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports
2021-01-14 19:33 ` [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports Andrey Konovalov
@ 2021-01-15 10:49 ` Catalin Marinas
2021-01-15 12:48 ` Andrey Konovalov
0 siblings, 1 reply; 5+ messages in thread
From: Catalin Marinas @ 2021-01-15 10:49 UTC (permalink / raw)
To: Andrey Konovalov
Cc: linux-arm-kernel, Marco Elver, Kevin Brodsky, Will Deacon,
Branislav Rankov, kasan-dev, linux-kernel, linux-mm,
Alexander Potapenko, Evgenii Stepanov, Andrey Ryabinin,
Andrew Morton, Vincenzo Frascino, Peter Collingbourne,
Dmitry Vyukov
On Thu, Jan 14, 2021 at 08:33:57PM +0100, Andrey Konovalov wrote:
> As of the "arm64: expose FAR_EL1 tag bits in siginfo" patch, the address
> that is passed to report_tag_fault has pointer tags in the format of 0x0X,
> while KASAN uses 0xFX format (note the difference in the top 4 bits).
>
> Fix up the pointer tag before calling kasan_report.
>
> Link: https://linux-review.googlesource.com/id/I9ced973866036d8679e8f4ae325de547eb969649
> Fixes: dceec3ff7807 ("arm64: expose FAR_EL1 tag bits in siginfo")
> Fixes: 4291e9ee6189 ("kasan, arm64: print report from tag fault handler")
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
> arch/arm64/mm/fault.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index 3c40da479899..a218f6f2fdc8 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -304,6 +304,8 @@ static void report_tag_fault(unsigned long addr, unsigned int esr,
> {
> bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
>
> + /* The format of KASAN tags is 0xF<x>. */
> + addr |= (0xF0UL << MTE_TAG_SHIFT);
> /*
> * SAS bits aren't set for all faults reported in EL1, so we can't
> * find out access size.
I already replied here but I don't see any change in v2:
https://lore.kernel.org/linux-arm-kernel/20210113165441.GC27045@gaia/
--
Catalin
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* Re: [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports
2021-01-15 10:49 ` Catalin Marinas
@ 2021-01-15 12:48 ` Andrey Konovalov
0 siblings, 0 replies; 5+ messages in thread
From: Andrey Konovalov @ 2021-01-15 12:48 UTC (permalink / raw)
To: Catalin Marinas
Cc: Linux ARM, Marco Elver, Kevin Brodsky, Will Deacon,
Branislav Rankov, kasan-dev, LKML, Linux Memory Management List,
Alexander Potapenko, Evgenii Stepanov, Andrey Ryabinin,
Andrew Morton, Vincenzo Frascino, Peter Collingbourne,
Dmitry Vyukov
On Fri, Jan 15, 2021 at 11:49 AM Catalin Marinas
<catalin.marinas@arm.com> wrote:
>
> On Thu, Jan 14, 2021 at 08:33:57PM +0100, Andrey Konovalov wrote:
> > As of the "arm64: expose FAR_EL1 tag bits in siginfo" patch, the address
> > that is passed to report_tag_fault has pointer tags in the format of 0x0X,
> > while KASAN uses 0xFX format (note the difference in the top 4 bits).
> >
> > Fix up the pointer tag before calling kasan_report.
> >
> > Link: https://linux-review.googlesource.com/id/I9ced973866036d8679e8f4ae325de547eb969649
> > Fixes: dceec3ff7807 ("arm64: expose FAR_EL1 tag bits in siginfo")
> > Fixes: 4291e9ee6189 ("kasan, arm64: print report from tag fault handler")
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > ---
> > arch/arm64/mm/fault.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> > index 3c40da479899..a218f6f2fdc8 100644
> > --- a/arch/arm64/mm/fault.c
> > +++ b/arch/arm64/mm/fault.c
> > @@ -304,6 +304,8 @@ static void report_tag_fault(unsigned long addr, unsigned int esr,
> > {
> > bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
> >
> > + /* The format of KASAN tags is 0xF<x>. */
> > + addr |= (0xF0UL << MTE_TAG_SHIFT);
> > /*
> > * SAS bits aren't set for all faults reported in EL1, so we can't
> > * find out access size.
>
> I already replied here but I don't see any change in v2:
>
> https://lore.kernel.org/linux-arm-kernel/20210113165441.GC27045@gaia/
Hi Catalin,
Sorry, Gmail decided to mark all your emails as spam for some reason,
so I didn't see any of them :(
I'll fix this in v3.
Thanks!
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2021-01-14 19:33 [PATCH v2 0/2] kasan: fixes for 5.11-rc Andrey Konovalov
2021-01-14 19:33 ` [PATCH v2 1/2] kasan, mm: fix conflicts with init_on_alloc/free Andrey Konovalov
2021-01-14 19:33 ` [PATCH v2 2/2] kasan, arm64: fix pointer tags in KASAN reports Andrey Konovalov
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2021-01-15 12:48 ` Andrey Konovalov
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