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home:michael-chang:test:grub:old
grub2
0001-loader-linux-Ensure-the-newc-pathname-is-N...
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File 0001-loader-linux-Ensure-the-newc-pathname-is-NULL-termin.patch of Package grub2
From 1dcab5bf3843abc997f7e7dba32e5dbcb9bf66b2 Mon Sep 17 00:00:00 2001 From: Gary Lin <glin@suse.com> Date: Fri, 25 Nov 2022 15:37:35 +0800 Subject: [PATCH 1/2] loader/linux: Ensure the newc pathname is NULL-terminated Per "man 5 cpio", the namesize in the cpio header includes the trailing NUL byte of the pathname and the pathname is followed by NUL bytes, but the current implementation ignores the trailing NUL byte when making the newc header. Although make_header() tries to 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. Assume that a file is created with 'echo -n aaaa > /boot/test12' and loaded by grub2: linux /boot/vmlinuz initrd newc:test12:/boot/test12 /boot/initrd The initrd command eventually invoked grub_initrd_load() and sent 't''e''s''t''1''2' to make_header() to generate the header: 00000070 30 37 30 37 30 31 33 30 31 43 41 30 44 45 30 30 |070701301CA0DE00| 00000080 30 30 38 31 41 34 30 30 30 30 30 33 45 38 30 30 |0081A4000003E800| 00000090 30 30 30 30 36 34 30 30 30 30 30 30 30 31 36 33 |0000640000000163| 000000a0 37 36 45 34 35 32 30 30 30 30 30 30 30 34 30 30 |76E4520000000400| 000000b0 30 30 30 30 30 38 30 30 30 30 30 30 31 33 30 30 |0000080000001300| 000000c0 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000| 000000d0 30 30 30 30 30 36 30 30 30 30 30 30 30 30 74 65 |00000600000000te| ^namesize 000000e0 73 74 31 32 61 61 61 61 30 37 30 37 30 31 30 30 |st12aaaa07070100| ^^ end of the pathname Since strlen("test12") + sizeof(struct newc_head) is 116 = 29 * 4, make_header() didn't pad the pathname, and the file content followed "test12" immediately. This violates the cpio format and may trigger such error during linux boot: Initramfs unpacking failed: ZSTD-compressed data is trunc To avoid the potential problems, this commit counts the trailing NUL byte in when calling make_header() and adjusts the initrd size accordingly. Now the header becomes 00000070 30 37 30 37 30 31 33 30 31 43 41 30 44 45 30 30 |070701301CA0DE00| 00000080 30 30 38 31 41 34 30 30 30 30 30 33 45 38 30 30 |0081A4000003E800| 00000090 30 30 30 30 36 34 30 30 30 30 30 30 30 31 36 33 |0000640000000163| 000000a0 37 36 45 34 35 32 30 30 30 30 30 30 30 34 30 30 |76E4520000000400| 000000b0 30 30 30 30 30 38 30 30 30 30 30 30 31 33 30 30 |0000080000001300| 000000c0 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000| 000000d0 30 30 30 30 30 37 30 30 30 30 30 30 30 30 74 65 |00000700000000te| ^namesize 000000e0 73 74 31 32 00 00 00 00 61 61 61 61 30 37 30 37 |st12....aaaa0707| ^^ end of the pathname Besides the trailing NUL byte, make_header() pads 3 more NUL bytes, and the user can safely read the pathname without a further check. To conform to the cpio format, the headers for "TRAILER!!!" are also adjusted to include the trailing NUL byte, not ignore it. Signed-off-by: Gary Lin <glin@suse.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> --- grub-core/loader/linux.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/grub-core/loader/linux.c b/grub-core/loader/linux.c index 8f0fad805..e4018e65e 100644 --- a/grub-core/loader/linux.c +++ b/grub-core/loader/linux.c @@ -130,12 +130,23 @@ insert_dir (const char *name, struct dir **root, n->name = grub_strndup (cb, ce - cb); if (ptr) { + /* + * Create the substring with the trailing NUL byte + * to be included in the cpio header. + */ + char *tmp_name = grub_strndup (name, ce - name); + if (!tmp_name) { + grub_free (n->name); + grub_free (n); + return grub_errno; + } 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)) { @@ -260,7 +271,7 @@ 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) || @@ -274,7 +285,7 @@ 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), &initrd_ctx->size)) goto overflow; free_dir (root); @@ -302,7 +313,7 @@ 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), &initrd_ctx->size)) goto overflow; free_dir (root); @@ -378,7 +389,7 @@ 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; @@ -406,7 +417,7 @@ 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); } free_dir (root); root = 0; -- 2.39.2
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