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b=IisiybxOoGQs9Wo+hB/KOZUyBLt+NgYjVM4mvhXQBQC17BlI3E/2ywsHXeARxYD+I HWseCM+NPPqlBpteLd+pE9e7Ak2d62iN48+RojGh3QpXhwSQKUPhcqezEgseYge7XX qeoDRsE/9l0+RR+v2C+nekuULwqCcaegZ8eY6+pGTgjUnpl9bQmK/1Ww9qWmwmfVVq ucfNUNGAzSxoxg61LYDYvnFBlylzrwx/zPNBbaS7lzxz1ojen3wJw+jZvJndhAB8ol iDWjS5h3d56vh6cgBswDE7dfXZ2aBkH7eqhtXiQXZx3JS/2niwrFYf+9+8uJ8NCLdT aQ3EUajXXtwZg== Date: Thu, 11 Jun 2026 17:28:50 +0300 From: Mike Rapoport To: Pratyush Yadav Cc: Tarun Sahu , Pasha Tatashin , 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: <2vxzmrx1qjuf.fsf@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2vxzmrx1qjuf.fsf@kernel.org> X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: rdwzynqpq9uzgjhgztdfnaj93dfk1yym X-Rspamd-Queue-Id: B667D20003 X-HE-Tag: 1781188138-222557 X-HE-Meta: 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 kU9qTXgW DCDnPWPOO/UcJeyBVUir1rgvi6CurQLDE+0suodO10yfLv3vzqSbY1rM61rjNhfksHQ12gCxaSQfcxjYE/e2W5EAS2uF2J32txerRUwdovfKAstEEBnmfW8xV2FuIrmQq+5kDa+mWoBYSBPShIsnaXg4ox03zLJKr6grcYZNiMHV6fDPuMNc0t4oz+/nZsfQFD11OG6P08iWtIenFFRHLChd9alS85vBD1wPKXCMulBCZSnYcgaM9sqj+pDmog87p0I6NRhGSp668xVdzwYgfZDsbbLMwwNsDNiU1yPLGOp9ZDZVB2rJZ1je0sKM+YYOTgAbF Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 > >> --- > >> 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. > -- > Regards, > Pratyush Yadav -- Sincerely yours, Mike.