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Thu, 11 Jun 2026 11:11:34 -0700 (PDT) Date: Thu, 11 Jun 2026 18:11:33 +0000 From: Pasha Tatashin To: Tarun Sahu Cc: Pasha Tatashin , Mike Rapoport , Pratyush Yadav , Andrew Morton , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/memfd_luo: validate serialized_data before conversion Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On 06-11 10:30, 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 Reviewed-by: Pasha Tatashin > --- > 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) > return; > > + ser = phys_to_virt(args->serialized_data); > + > if (ser->nr_folios) { > folios_ser = kho_restore_vmalloc(&ser->folios); > if (!folios_ser) > @@ -522,10 +523,11 @@ static int memfd_luo_retrieve(struct liveupdate_file_op_args *args) > struct file *file; > int err; > > - ser = phys_to_virt(args->serialized_data); > - if (!ser) > + if (!args->serialized_data) > return -EINVAL; > > + ser = phys_to_virt(args->serialized_data); > + > /* Make sure the file only has seals supported by this version. */ > if (ser->seals & ~MEMFD_LUO_ALL_SEALS) { > err = -EOPNOTSUPP; > > base-commit: 9716c086c8e8b141d35aa61f2e96a2e83de212a7 > -- > 2.54.0.1099.g489fc7bff1-goog >