| Message ID | 20210122143748.50089-3-vincenzo.frascino@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kasan: Fix metadata detection for KASAN_HW_TAGS | expand |
On Fri, Jan 22, 2021 at 3:38 PM Vincenzo Frascino <vincenzo.frascino@arm.com> wrote: > > With the introduction of KASAN_HW_TAGS, kasan_report() dereferences > the address passed as a parameter. It doesn't dereference the address, it accesses the metadata. And only when addr_has_metadata() succeeds. > > Add a comment to make sure that the preconditions to the function are > explicitly clarified. > > Note: An invalid address (e.g. NULL) passed to the function when, > KASAN_HW_TAGS is enabled, leads to a kernel panic. This is no longer true, right? Commit description needs to be updated. > > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> > Cc: Alexander Potapenko <glider@google.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Leon Romanovsky <leonro@mellanox.com> > Cc: Andrey Konovalov <andreyknvl@google.com> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > --- > include/linux/kasan.h | 7 +++++++ > mm/kasan/kasan.h | 2 +- > 2 files changed, 8 insertions(+), 1 deletion(-) > > diff --git a/include/linux/kasan.h b/include/linux/kasan.h > index fe1ae73ff8b5..0aea9e2a2a01 100644 > --- a/include/linux/kasan.h > +++ b/include/linux/kasan.h > @@ -333,6 +333,13 @@ static inline void *kasan_reset_tag(const void *addr) > return (void *)arch_kasan_reset_tag(addr); > } > > +/** > + * kasan_report - print a report about a bad memory access detected by KASAN > + * @addr: address of the bad access > + * @size: size of the bad access > + * @is_write: whether the bad access is a write or a read > + * @ip: instruction pointer for the accessibility check or the bad access itself > + */ Looks good, thanks! > bool kasan_report(unsigned long addr, size_t size, > bool is_write, unsigned long ip); > > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index cc4d9e1d49b1..8c706e7652f2 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -209,7 +209,7 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, > > static inline bool addr_has_metadata(const void *addr) > { > - return true; > + return (is_vmalloc_addr(addr) || virt_addr_valid(addr)); > } Let's put this change into a separate patch. > > #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */ > -- > 2.30.0 >
On 1/22/21 2:46 PM, Andrey Konovalov wrote: > On Fri, Jan 22, 2021 at 3:38 PM Vincenzo Frascino > <vincenzo.frascino@arm.com> wrote: >> >> With the introduction of KASAN_HW_TAGS, kasan_report() dereferences >> the address passed as a parameter. > > It doesn't dereference the address, it accesses the metadata. And only > when addr_has_metadata() succeeds. > Yes, this is correct. Seems I forgot again to unstash something. Will fix it in v4. >> >> Add a comment to make sure that the preconditions to the function are >> explicitly clarified. >> >> Note: An invalid address (e.g. NULL) passed to the function when, >> KASAN_HW_TAGS is enabled, leads to a kernel panic. > > This is no longer true, right? Commit description needs to be updated. > >> >> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> >> Cc: Alexander Potapenko <glider@google.com> >> Cc: Dmitry Vyukov <dvyukov@google.com> >> Cc: Leon Romanovsky <leonro@mellanox.com> >> Cc: Andrey Konovalov <andreyknvl@google.com> >> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> >> --- >> include/linux/kasan.h | 7 +++++++ >> mm/kasan/kasan.h | 2 +- >> 2 files changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/include/linux/kasan.h b/include/linux/kasan.h >> index fe1ae73ff8b5..0aea9e2a2a01 100644 >> --- a/include/linux/kasan.h >> +++ b/include/linux/kasan.h >> @@ -333,6 +333,13 @@ static inline void *kasan_reset_tag(const void *addr) >> return (void *)arch_kasan_reset_tag(addr); >> } >> >> +/** >> + * kasan_report - print a report about a bad memory access detected by KASAN >> + * @addr: address of the bad access >> + * @size: size of the bad access >> + * @is_write: whether the bad access is a write or a read >> + * @ip: instruction pointer for the accessibility check or the bad access itself >> + */ > > Looks good, thanks! > >> bool kasan_report(unsigned long addr, size_t size, >> bool is_write, unsigned long ip); >> >> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h >> index cc4d9e1d49b1..8c706e7652f2 100644 >> --- a/mm/kasan/kasan.h >> +++ b/mm/kasan/kasan.h >> @@ -209,7 +209,7 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, >> >> static inline bool addr_has_metadata(const void *addr) >> { >> - return true; >> + return (is_vmalloc_addr(addr) || virt_addr_valid(addr)); >> } > > Let's put this change into a separate patch. > Ok, it will be done in v4. >> >> #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */ >> -- >> 2.30.0 >>
diff --git a/include/linux/kasan.h b/include/linux/kasan.h index fe1ae73ff8b5..0aea9e2a2a01 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -333,6 +333,13 @@ static inline void *kasan_reset_tag(const void *addr) return (void *)arch_kasan_reset_tag(addr); } +/** + * kasan_report - print a report about a bad memory access detected by KASAN + * @addr: address of the bad access + * @size: size of the bad access + * @is_write: whether the bad access is a write or a read + * @ip: instruction pointer for the accessibility check or the bad access itself + */ bool kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip); diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index cc4d9e1d49b1..8c706e7652f2 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -209,7 +209,7 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, static inline bool addr_has_metadata(const void *addr) { - return true; + return (is_vmalloc_addr(addr) || virt_addr_valid(addr)); } #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
With the introduction of KASAN_HW_TAGS, kasan_report() dereferences the address passed as a parameter. Add a comment to make sure that the preconditions to the function are explicitly clarified. Note: An invalid address (e.g. NULL) passed to the function when, KASAN_HW_TAGS is enabled, leads to a kernel panic. Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Leon Romanovsky <leonro@mellanox.com> Cc: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> --- include/linux/kasan.h | 7 +++++++ mm/kasan/kasan.h | 2 +- 2 files changed, 8 insertions(+), 1 deletion(-)