diff options
| author | Hugh Dickins <[email protected]> | 2020-08-20 17:42:17 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2020-08-21 09:52:53 -0700 |
| commit | c17c3dc9d08b9aad9a55a1e53f205187972f448e (patch) | |
| tree | 845d5502902b8fc632667474e99d7c2b9333b61e | |
| parent | 71e843295c680898959b22dc877ae3839cc22470 (diff) | |
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).
Fixes: 5a52c9df62b4 ("uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT")
Reported-by: syzbot <[email protected]>
Signed-off-by: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Srikar Dronamraju <[email protected]>
Acked-by: Song Liu <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: <[email protected]> [5.4+]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | kernel/events/uprobes.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 649fd53dc9ad..0e18aaf23a7b 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -205,7 +205,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, 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); |