| Message ID | 20200819024925.wmG-vrVrv%akpm@linux-foundation.org |
|---|---|
| State | New |
| Headers | show |
| Series | + uprobes-__replace_page-avoid-bug-in-munlock_vma_page.patch added to -mm tree | expand |
--- a/kernel/events/uprobes.c~uprobes-__replace_page-avoid-bug-in-munlock_vma_page +++ a/kernel/events/uprobes.c @@ -205,7 +205,7 @@ static int __replace_page(struct vm_area try_to_free_swap(old_page); page_vma_mapped_walk_done(&pvmw); - if (vma->vm_flags & VM_LOCKED) + if ((vma->vm_flags & VM_LOCKED) && !PageCompound(old_page)) munlock_vma_page(old_page); put_page(old_page);
The patch titled Subject: uprobes: __replace_page() avoid BUG in munlock_vma_page() has been added to the -mm tree. Its filename is uprobes-__replace_page-avoid-bug-in-munlock_vma_page.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/uprobes-__replace_page-avoid-bug-in-munlock_vma_page.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/uprobes-__replace_page-avoid-bug-in-munlock_vma_page.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Hugh Dickins <hughd@google.com> Subject: uprobes: __replace_page() avoid BUG in munlock_vma_page() syzbot crashed on the VM_BUG_ON_PAGE(PageTail) in munlock_vma_page(), when called from uprobes __replace_page(). Which of many ways to fix it? Settled on not calling when PageCompound (since Head and Tail are equals in this context, PageCompound the usual check in uprobes.c, and the prior use of FOLL_SPLIT_PMD will have cleared PageMlocked already). Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008161338360.20413@eggly.anvils Fixes: 5a52c9df62b4 ("uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT") Signed-off-by: Hugh Dickins <hughd@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Acked-by: Song Liu <songliubraving@fb.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> [5.4+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- kernel/events/uprobes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)