Commit c9811b22 authored by Jann Horn's avatar Jann Horn Committed by Chen Ridong
Browse files

comedi: Flush partial mappings in error case 

stable inclusion
from stable-v5.10.231
commit b9322408d83accc8b96322bc7356593206288c56
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBDHGS
CVE: CVE-2024-53148

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b9322408d83accc8b96322bc7356593206288c56



--------------------------------

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: ed9eccbe ("Staging: add comedi core")
Signed-off-by: default avatarJann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20241017-comedi-tlb-v3-1-16b82f9372ce@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarChen Ridong <chenridong@huawei.com>
parent e804018e

drivers/staging/comedi/comedi_fops.c

+12 −0
Original line number Diff line number Diff line
@@ -2402,6 +2402,18 @@ 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) {