On 4/27/23 16:09, Vlastimil Babka wrote:
|later. Alternatively it could be added to mm/mm-stable and upcoming 6.4 pull request, but then the stable backport would need adjustment. It's up to Linus and Andrew. |
This version applies on mm/mm-stable. Paragraph about case 8 is removed as that case sets vma_pgoff explicitly itself.
----8<---- From dea6d87bdad1fbb21f987dba96c55195fb88e7b4 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka vbabka@suse.cz Date: Thu, 27 Apr 2023 15:28:41 +0200 Subject: [PATCH] mm/mremap: fix vm_pgoff in vma_merge() case 3
After upgrading build guests to v6.3, rpm started segfaulting for specific packages, which was bisected to commit 0503ea8f5ba7 ("mm/mmap: remove __vma_adjust()"). rpm is doing many mremap() operations with file mappings of its db. The problem is that in vma_merge() case 3 (we merge with the next vma, expanding it downwards) vm_pgoff is not adjusted as it should when vm_start changes. As a result the rpm process most likely sees data from the wrong offset of the file. Fix the vm_pgoff calculation.
Reported-and-bisected-by: Jiri Slaby jirislaby@kernel.org Reported-and-tested-by: Fabian Vogt fvogt@suse.com Link: https://bugzilla.suse.com/show_bug.cgi?id=1210903 Fixes: 0503ea8f5ba7 ("mm/mmap: remove __vma_adjust()") Signed-off-by: Vlastimil Babka vbabka@suse.cz Cc: stable@vger.kernel.org --- mm/mmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/mmap.c b/mm/mmap.c index 536bbb8fa0ae..5522130ae606 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1008,7 +1008,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, vma = next; /* case 3 */ vma_start = addr; vma_end = next->vm_end; - vma_pgoff = next->vm_pgoff; + vma_pgoff = next->vm_pgoff - pglen; if (curr) { /* case 8 */ vma_pgoff = curr->vm_pgoff; remove = curr;