| Message ID | 20240621113706.315500-19-iii@linux.ibm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | kmsan: Enable on s390 | expand |
On 6/21/24 1:35 PM, Ilya Leoshkevich wrote: > Even though the KMSAN warnings generated by memchr_inv() are suppressed > by metadata_access_enable(), its return value may still be poisoned. > > The reason is that the last iteration of memchr_inv() returns > `*start != value ? start : NULL`, where *start is poisoned. Because of > this, somewhat counterintuitively, the shadow value computed by > visitSelectInst() is equal to `(uintptr_t)start`. > > One possibility to fix this, since the intention behind guarding > memchr_inv() behind metadata_access_enable() is to touch poisoned > metadata without triggering KMSAN, is to unpoison its return value. > However, this approach is too fragile. So simply disable the KMSAN > checks in the respective functions. > > Reviewed-by: Alexander Potapenko <glider@google.com> > Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/slub.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index b050e528112c..fcd68fcea4ab 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -1176,9 +1176,16 @@ static void restore_bytes(struct kmem_cache *s, char *message, u8 data, > memset(from, data, to - from); > } > > -static int check_bytes_and_report(struct kmem_cache *s, struct slab *slab, > - u8 *object, char *what, > - u8 *start, unsigned int value, unsigned int bytes) > +#ifdef CONFIG_KMSAN > +#define pad_check_attributes noinline __no_kmsan_checks > +#else > +#define pad_check_attributes > +#endif > + > +static pad_check_attributes int > +check_bytes_and_report(struct kmem_cache *s, struct slab *slab, > + u8 *object, char *what, > + u8 *start, unsigned int value, unsigned int bytes) > { > u8 *fault; > u8 *end; > @@ -1270,7 +1277,8 @@ static int check_pad_bytes(struct kmem_cache *s, struct slab *slab, u8 *p) > } > > /* Check the pad bytes at the end of a slab page */ > -static void slab_pad_check(struct kmem_cache *s, struct slab *slab) > +static pad_check_attributes void > +slab_pad_check(struct kmem_cache *s, struct slab *slab) > { > u8 *start; > u8 *fault;
diff --git a/mm/slub.c b/mm/slub.c index b050e528112c..fcd68fcea4ab 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1176,9 +1176,16 @@ static void restore_bytes(struct kmem_cache *s, char *message, u8 data, memset(from, data, to - from); } -static int check_bytes_and_report(struct kmem_cache *s, struct slab *slab, - u8 *object, char *what, - u8 *start, unsigned int value, unsigned int bytes) +#ifdef CONFIG_KMSAN +#define pad_check_attributes noinline __no_kmsan_checks +#else +#define pad_check_attributes +#endif + +static pad_check_attributes int +check_bytes_and_report(struct kmem_cache *s, struct slab *slab, + u8 *object, char *what, + u8 *start, unsigned int value, unsigned int bytes) { u8 *fault; u8 *end; @@ -1270,7 +1277,8 @@ static int check_pad_bytes(struct kmem_cache *s, struct slab *slab, u8 *p) } /* Check the pad bytes at the end of a slab page */ -static void slab_pad_check(struct kmem_cache *s, struct slab *slab) +static pad_check_attributes void +slab_pad_check(struct kmem_cache *s, struct slab *slab) { u8 *start; u8 *fault;