Mike Rapoport <[email protected]> writes: > On Thu, Jun 11, 2026 at 06:11:13PM +0000, Pasha Tatashin wrote: >> On 06-11 17:28, Mike Rapoport wrote: >> > On Thu, Jun 11, 2026 at 03:37:12PM +0200, Pratyush Yadav wrote: >> > > On Thu, Jun 11 2026, Mike Rapoport wrote: >> > > >> > > > On Thu, Jun 11, 2026 at 10:30:03AM +0000, Tarun Sahu wrote: >> > > >> In memfd_luo_finish() and memfd_luo_retrieve(), phys_to_virt() was >> > > >> called >> > > >> on args->serialized_data before checking if the physical address is >> > > >> valid. >> > > >> Since physical address 0 does not map to virtual NULL (due to direct >> > > >> mapping offsets), the subsequent check 'if (!ser)' was ineffective at >> > > >> catching a missing serialized_data, leading to unsafe dereferences >> > > >> later. >> > > >> >> > > >> Validate that args->serialized_data is non-zero before calling >> > > >> phys_to_virt(). >> > > >> >> > > >> Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd") >> > > >> Signed-off-by: Tarun Sahu <[email protected]> >> > > >> --- >> > > >> mm/memfd_luo.c | 10 ++++++---- >> > > >> 1 file changed, 6 insertions(+), 4 deletions(-) >> > > >> >> > > >> diff --git a/mm/memfd_luo.c b/mm/memfd_luo.c >> > > >> index 59de210bee5f..10f3983b0060 100644 >> > > >> --- a/mm/memfd_luo.c >> > > >> +++ b/mm/memfd_luo.c >> > > >> @@ -397,10 +397,11 @@ static void memfd_luo_finish(struct >> > > >> liveupdate_file_op_args *args) >> > > >> if (args->retrieve_status) >> > > >> return; >> > > >> >> > > >> - ser = phys_to_virt(args->serialized_data); >> > > >> - if (!ser) >> > > >> + if (!args->serialized_data) >> > > > >> > > > We really should make args->serialized_data a KHOSER_PTR >> > > >> > > Hmm, that would also be a good idea. I suppose then it would be a better >> > > to directly convert to using KHOSER_PTR() instead of this patch? >> > >> > Makes sense. >> >> I think we should systematically cover all phys_to_virt conversions >> and add KOSHER_PTR() , instead of an ad-hoc approach of adding it as we >> go. So, let's take this patch and do a series where we properly convert >> everything and provide guidance for others to use going forward. > > It's too late for this patch for -rc1. So let's systematically convert all > 4 or 5 direct phys_to_virt() conversions in the next cycle and be done with > it. > > We have enough time to make it by -rc2.
I am already working on converitng them to use KHOSER_PTR. I have patch ready, Will send soon after some testing. ~Tarun > >> Pasha > > -- > Sincerely yours, > Mike.
