Hi Akashi,
On 18/05/18 08:42, AKASHI Takahiro wrote:
> On Fri, May 18, 2018 at 04:11:35PM +0900, AKASHI Takahiro wrote:
>> On Tue, May 15, 2018 at 05:20:00PM +0100, James Morse wrote:
>>> On 25/04/18 07:26, AKASHI Takahiro wrote:
>>>> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
>>>> index f9ebf54ca247..b3b9b1725d8a 100644
>>>> --- a/arch/arm64/kernel/machine_kexec_file.c
>>>> +++ b/arch/arm64/kernel/machine_kexec_file.c
>>>> @@ -55,3 +74,144 @@ int arch_kexec_walk_mem(struct kexec_buf *kbuf,
>>>> + buf = vmalloc(buf_size);
>>>> + if (!buf) {
>>>> + ret = -ENOMEM;
>>>> + goto out_err;
>>>> + }
>>>> +
>>>> + ret = fdt_open_into(initial_boot_params, buf, buf_size);
>>>> + if (ret)
>>>> + goto out_err;
>>>> +
>>>> + nodeoffset = fdt_path_offset(buf, "/chosen");
>>>> + if (nodeoffset < 0)
>>>> + goto out_err;
>>>> +
>>>> + /* add bootargs */
>>>> + if (cmdline) {
>>>> + ret = fdt_setprop(buf, nodeoffset, "bootargs",
>>>> + cmdline, cmdline_len + 1);
>>>
>>> fdt_setprop_string()?
>>
>> OK
>
> cmdline_len is passed by system call, kexec_file_load(), and this means
> that we can't believe that cmdline is always terminated with '\0'.
Yuck, we expect user-space to tell us how long the string is. It may be worth a
comment that it isn't necessarily null-terminated, as that is surprising!
(I assume the DT's property length is enough to make that safe for the new
kernel to read).
>>>> + /* within 1GB-aligned window of up to 32GB in size */
>>>> + kbuf.buf_max = round_down(kern_seg->mem, SZ_1G)
>>>> + + (unsigned long)SZ_1G * 32;
>>>> + kbuf.top_down = false;
>>>> +
>>>> + ret = kexec_add_buffer(&kbuf);
>>>> + if (ret)
>>>> + goto out_err;
>>>> + initrd_load_addr = kbuf.mem;
>>>> +
>>>> + pr_debug("Loaded initrd at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
>>>> + initrd_load_addr, initrd_len, initrd_len);
>>>> + }
>>>> +
>>>> + /* load dtb blob */
>>>> + ret = setup_dtb(image, initrd_load_addr, initrd_len,
>>>> + cmdline, cmdline_len, &dtb, &dtb_len);
>>>> + if (ret) {
>>>> + pr_err("Preparing for new dtb failed\n");
>>>> + goto out_err;
>>>> + }
>>>> +
>>>> + kbuf.buffer = dtb;
>>>> + kbuf.bufsz = dtb_len;
>>>> + kbuf.memsz = dtb_len;
>>>> + /* not across 2MB boundary */
>>>> + kbuf.buf_align = SZ_2M;
>>>> + kbuf.buf_max = ULONG_MAX;
>>>> + kbuf.top_down = true;
>>>> +
>>>> + ret = kexec_add_buffer(&kbuf);
>>>> + if (ret)
>>>> + goto out_err;
>>>> + image->arch.dtb_mem = kbuf.mem;
>>>> + image->arch.dtb_buf = dtb;
>>>> +
>>>> + pr_debug("Loaded dtb at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
>>>> + kbuf.mem, dtb_len, dtb_len);
>>>> +
>>>> + return 0;
>>>> +
>>>> +out_err:
>>>> + vfree(dtb);
>>>> + image->arch.dtb_buf = NULL;
>>>
>>> Won't kimage_file_post_load_cleanup() always be called if we return an error
>>> here? Why not leave the free()ing until then?
>>
>> Right.
>> The reason why I left the code here was that we'd better locally clean up
>> all the stuff that were locally allocated if we trivially need to (and can)
>> do so.
>>
>> As it's redundant, I will remove it.
>
> will remove only "image->arch.dtb_buf = NULL."
Ah, because you haven't set the arch.dtb_buf pointer yet.
What about in patch 7 where you expect kimage_file_prepare_segments() to call
arch_kimage_file_post_load_cleanup() to free the arch.elf_headers? I'd expect
the free()ing to always happen in one place.
Thanks,
James
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