From bf54d44ad1ae7b56c1beb972662d0f232af37e88 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Tue, 11 Mar 2025 08:51:19 +0900 Subject: [PATCH] comedi: Flush partial mappings in error case BugLink: https://bugs.launchpad.net/bugs/2101915 commit ce8f9fb651fac95dd41f69afe54d935420b945bd upstream. If some remap_pfn_range() calls succeeded before one failed, we still have buffer pages mapped into the userspace page tables when we drop the buffer reference with comedi_buf_map_put(bm). The userspace mappings are only cleaned up later in the mmap error path. Fix it by explicitly flushing all mappings in our VMA on the error path. See commit 79a61cc3fc04 ("mm: avoid leaving partial pfn mappings around in error case"). Cc: stable@vger.kernel.org Fixes: ed9eccbe8970 ("Staging: add comedi core") Signed-off-by: Jann Horn Link: https://lore.kernel.org/r/20241017-comedi-tlb-v3-1-16b82f9372ce@google.com Signed-off-by: Greg Kroah-Hartman CVE-2024-53148 Signed-off-by: Koichiro Den Signed-off-by: Stefan Bader --- drivers/comedi/comedi_fops.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c index 1b481731df96..b9df9b19d4bd 100644 --- a/drivers/comedi/comedi_fops.c +++ b/drivers/comedi/comedi_fops.c @@ -2407,6 +2407,18 @@ static int comedi_mmap(struct file *file, struct vm_area_struct *vma) start += PAGE_SIZE; } + +#ifdef CONFIG_MMU + /* + * Leaving behind a partial mapping of a buffer we're about to + * drop is unsafe, see remap_pfn_range_notrack(). + * We need to zap the range here ourselves instead of relying + * on the automatic zapping in remap_pfn_range() because we call + * remap_pfn_range() in a loop. + */ + if (retval) + zap_vma_ptes(vma, vma->vm_start, size); +#endif } if (retval == 0) {