Messages in this thread | | | Date | Wed, 2 Jun 2021 10:41:28 -0700 | From | Kees Cook <> | Subject | Re: [PATCH 1/1] pgo: Fix allocate_node() handling of non-vmlinux nodes. |
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On Wed, Jun 02, 2021 at 03:57:04AM +0300, Jarmo Tiitto wrote: > Currently allocate_node() will reserve nodes even if *p > doesn't point into __llvm_prf_data_start - __llvm_prf_data_end > range. > > Fix it by checking if p points into vmlinux range > and otherwise return NULL. > > Signed-off-by: Jarmo Tiitto <jarmo.tiitto@gmail.com> > --- > kernel/pgo/instrument.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/kernel/pgo/instrument.c b/kernel/pgo/instrument.c > index 0e07ee1b17d9..9bca535dfa91 100644 > --- a/kernel/pgo/instrument.c > +++ b/kernel/pgo/instrument.c > @@ -55,6 +55,10 @@ void prf_unlock(unsigned long flags) > static struct llvm_prf_value_node *allocate_node(struct llvm_prf_data *p, > u32 index, u64 value) > { > + /* check if p points into vmlinux. If not, don't allocate. */ > + if (p < __llvm_prf_data_start || p >= __llvm_prf_data_end) > + return NULL;
This should be a tighter check (struct llvm_prf_data has size, so just checking for p < __llvm_prf_data_end isn't sufficient. I recommend using the memory_contains() helper.
And I think this should be louder as it's entirely unexpected right now. Perhaps:
if (WARN_ON_ONCE(!memory_contains(__llvm_prf_data_start, __llvm_prf_data_end, p, sizeof(*p)))) return NULL;
> + > if (&__llvm_prf_vnds_start[current_node + 1] >= __llvm_prf_vnds_end) > return NULL; /* Out of nodes */ > > -- > 2.31.1 >
-- Kees Cook
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