copy_oldmem_page() maps a page of the old kernel that isn't in the linear mapping with ioremap_cache() and copies from it without checking whether the mapping worked. If it didn't, the copy reads from an offset into the NULL page. That oopses unless the copy happens to be a user copy, whose exception table entries turn the fault into a short copy.
Return -ENOMEM like the other architectures do. read_from_oldmem() turns that into -EFAULT like any other short copy. Reported-by: Chris Mason <[email protected]> Fixes: 54c32021eb6f ("[PATCH] powerpc: Add arch-dependent copy_oldmem_page") Cc: [email protected] Signed-off-by: Christian Brauner (Amutable) <[email protected]> --- arch/powerpc/kernel/crash_dump.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c index 103b6605dd68..1543917bd3e1 100644 --- a/arch/powerpc/kernel/crash_dump.c +++ b/arch/powerpc/kernel/crash_dump.c @@ -86,6 +86,8 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, csize = copy_to_iter(vaddr + offset, csize, iter); } else { vaddr = ioremap_cache(paddr, PAGE_SIZE); + if (!vaddr) + return -ENOMEM; csize = copy_to_iter(vaddr + offset, csize, iter); iounmap(vaddr); } -- 2.53.0
