On Wed, Nov 23, 2022 at 02:40:21PM +0800, Gary Lin via Grub-devel wrote:
> Per "man 5 cpio", the namesize in the cpio header includes the trailing
> NULL byte of the pathname and the pathname is followed by NULL bytes, but
s/NULL/NUL/ and below please...
> the current implementation excludes the trailing NULL byte when making
> the newc header plus the pathname. Although make_header() would pad the
> pathname string, the padding won't happen when strlen(name) +
> sizeof(struct newc_head) is a multiple of 4, and the non-NULL-terminated
> pathname may lead to unexpected results.
>
> For example, when loading linux with the following command:
>
> linux /boot/vmlinuz
> initrd newc:test12:/boot/test12 /boot/initrd
>
> Since strlen("test12") + sizeof(struct newc_head) is 116 = 29 * 4, there
> is no padding for the pathname, and the following error may show during
> linux boot:
>
> Initramfs unpacking failed: ZSTD-compressed data is trunc
>
> To avoid the potential problems, this commit includes the NULL byte when
> calling make_header() and adjusts the initrd size accordingly.
>
> Signed-off-by: Gary Lin <g...@suse.com>
> ---
> grub-core/loader/linux.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/grub-core/loader/linux.c b/grub-core/loader/linux.c
> index 830360172..2b26d293f 100644
> --- a/grub-core/loader/linux.c
> +++ b/grub-core/loader/linux.c
> @@ -127,12 +127,14 @@ insert_dir (const char *name, struct dir **root,
> n->name = grub_strndup (cb, ce - cb);
> if (ptr)
> {
> + char *tmp_name = grub_strndup (name, ce - name);
Why is this needed? And if it is needed you have to check for NULL here.
I do not mention that formatting is broken too. You use spaces instead
of tabs here and below.
> grub_dprintf ("linux", "Creating directory %s, %s\n", name, ce);
> - ptr = make_header (ptr, name, ce - name,
> + ptr = make_header (ptr, tmp_name, ce - name + 1,
> 040777, 0);
> + grub_free (tmp_name);
> }
> if (grub_add (*size,
> - ALIGN_UP ((ce - (char *) name)
> + ALIGN_UP ((ce - (char *) name + 1)
> + sizeof (struct newc_head), 4),
> size))
> {
> @@ -191,7 +193,7 @@ grub_initrd_init (int argc, char *argv[],
> grub_initrd_close (initrd_ctx);
> return grub_errno;
> }
> - name_len = grub_strlen (initrd_ctx->components[i].newc_name);
> + name_len = grub_strlen (initrd_ctx->components[i].newc_name) + 1;
> if (grub_add (initrd_ctx->size,
> ALIGN_UP (sizeof (struct newc_head) + name_len, 4),
> &initrd_ctx->size) ||
> @@ -205,7 +207,7 @@ grub_initrd_init (int argc, char *argv[],
> {
> if (grub_add (initrd_ctx->size,
> ALIGN_UP (sizeof (struct newc_head)
> - + sizeof ("TRAILER!!!") - 1, 4),
> + + sizeof ("TRAILER!!!"), 4),
This change looks strange and begs for explanation in the patch.
> &initrd_ctx->size))
> goto overflow;
> free_dir (root);
> @@ -233,7 +235,7 @@ grub_initrd_init (int argc, char *argv[],
> initrd_ctx->size = ALIGN_UP (initrd_ctx->size, 4);
> if (grub_add (initrd_ctx->size,
> ALIGN_UP (sizeof (struct newc_head)
> - + sizeof ("TRAILER!!!") - 1, 4),
> + + sizeof ("TRAILER!!!"), 4),
Ditto and bellow...
> &initrd_ctx->size))
> goto overflow;
> free_dir (root);
> @@ -304,7 +306,7 @@ grub_initrd_load (struct grub_linux_initrd_context
> *initrd_ctx,
> }
> else if (newc)
> {
> - ptr = make_header (ptr, "TRAILER!!!", sizeof ("TRAILER!!!") - 1,
> + ptr = make_header (ptr, "TRAILER!!!", sizeof ("TRAILER!!!"),
> 0, 0);
> free_dir (root);
> root = 0;
> @@ -327,7 +329,7 @@ grub_initrd_load (struct grub_linux_initrd_context
> *initrd_ctx,
> {
> grub_memset (ptr, 0, ALIGN_UP_OVERHEAD (cursize, 4));
> ptr += ALIGN_UP_OVERHEAD (cursize, 4);
> - ptr = make_header (ptr, "TRAILER!!!", sizeof ("TRAILER!!!") - 1, 0, 0);
> + ptr = make_header (ptr, "TRAILER!!!", sizeof ("TRAILER!!!"), 0, 0);
Daniel
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