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From 68a09a74f6d726d79709847f3671c0a08e4fb5a0 Mon Sep 17 00:00:00 2001
From: Colin Watson <cjwatson@debian.org>
Date: Sat, 25 Jul 2020 12:15:37 +0100
Subject: [PATCH 9/9] linux: Fix integer overflows in initrd size handling
These could be triggered by a crafted filesystem with very large files.
Fixes: CVE-2020-15707
Upstream-Status: Backport [commit e7b8856f8be3292afdb38d2e8c70ad8d62a61e10
from https://git.savannah.gnu.org/git/grub.git]
Signed-off-by: Colin Watson <cjwatson@debian.org>
Reviewed-by: Jan Setje-Eilers <jan.setjeeilers@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Yongxin Liu <yongxin.liu@windriver.com>
---
grub-core/loader/linux.c | 74 +++++++++++++++++++++++++++++++++++-------------
1 file changed, 54 insertions(+), 20 deletions(-)
diff --git a/grub-core/loader/linux.c b/grub-core/loader/linux.c
index 471b214..8c8565a 100644
--- a/grub-core/loader/linux.c
+++ b/grub-core/loader/linux.c
@@ -4,6 +4,7 @@
#include <grub/misc.h>
#include <grub/file.h>
#include <grub/mm.h>
+#include <grub/safemath.h>
struct newc_head
{
@@ -98,13 +99,13 @@ free_dir (struct dir *root)
grub_free (root);
}
-static grub_size_t
+static grub_err_t
insert_dir (const char *name, struct dir **root,
- grub_uint8_t *ptr)
+ grub_uint8_t *ptr, grub_size_t *size)
{
struct dir *cur, **head = root;
const char *cb, *ce = name;
- grub_size_t size = 0;
+ *size = 0;
while (1)
{
for (cb = ce; *cb == '/'; cb++);
@@ -130,14 +131,22 @@ insert_dir (const char *name, struct dir **root,
ptr = make_header (ptr, name, ce - name,
040777, 0);
}
- size += ALIGN_UP ((ce - (char *) name)
- + sizeof (struct newc_head), 4);
+ if (grub_add (*size,
+ ALIGN_UP ((ce - (char *) name)
+ + sizeof (struct newc_head), 4),
+ size))
+ {
+ grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow is detected"));
+ grub_free (n->name);
+ grub_free (n);
+ return grub_errno;
+ }
*head = n;
cur = n;
}
root = &cur->next;
}
- return size;
+ return GRUB_ERR_NONE;
}
grub_err_t
@@ -173,26 +182,33 @@ grub_initrd_init (int argc, char *argv[],
eptr = grub_strchr (ptr, ':');
if (eptr)
{
+ grub_size_t dir_size, name_len;
+
initrd_ctx->components[i].newc_name = grub_strndup (ptr, eptr - ptr);
- if (!initrd_ctx->components[i].newc_name)
+ if (!initrd_ctx->components[i].newc_name ||
+ insert_dir (initrd_ctx->components[i].newc_name, &root, 0,
+ &dir_size))
{
grub_initrd_close (initrd_ctx);
return grub_errno;
}
- initrd_ctx->size
- += ALIGN_UP (sizeof (struct newc_head)
- + grub_strlen (initrd_ctx->components[i].newc_name),
- 4);
- initrd_ctx->size += insert_dir (initrd_ctx->components[i].newc_name,
- &root, 0);
+ name_len = grub_strlen (initrd_ctx->components[i].newc_name);
+ if (grub_add (initrd_ctx->size,
+ ALIGN_UP (sizeof (struct newc_head) + name_len, 4),
+ &initrd_ctx->size) ||
+ grub_add (initrd_ctx->size, dir_size, &initrd_ctx->size))
+ goto overflow;
newc = 1;
fname = eptr + 1;
}
}
else if (newc)
{
- initrd_ctx->size += ALIGN_UP (sizeof (struct newc_head)
- + sizeof ("TRAILER!!!") - 1, 4);
+ if (grub_add (initrd_ctx->size,
+ ALIGN_UP (sizeof (struct newc_head)
+ + sizeof ("TRAILER!!!") - 1, 4),
+ &initrd_ctx->size))
+ goto overflow;
free_dir (root);
root = 0;
newc = 0;
@@ -208,19 +224,29 @@ grub_initrd_init (int argc, char *argv[],
initrd_ctx->nfiles++;
initrd_ctx->components[i].size
= grub_file_size (initrd_ctx->components[i].file);
- initrd_ctx->size += initrd_ctx->components[i].size;
+ if (grub_add (initrd_ctx->size, initrd_ctx->components[i].size,
+ &initrd_ctx->size))
+ goto overflow;
}
if (newc)
{
initrd_ctx->size = ALIGN_UP (initrd_ctx->size, 4);
- initrd_ctx->size += ALIGN_UP (sizeof (struct newc_head)
- + sizeof ("TRAILER!!!") - 1, 4);
+ if (grub_add (initrd_ctx->size,
+ ALIGN_UP (sizeof (struct newc_head)
+ + sizeof ("TRAILER!!!") - 1, 4),
+ &initrd_ctx->size))
+ goto overflow;
free_dir (root);
root = 0;
}
return GRUB_ERR_NONE;
+
+ overflow:
+ free_dir (root);
+ grub_initrd_close (initrd_ctx);
+ return grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow is detected"));
}
grub_size_t
@@ -261,8 +287,16 @@ grub_initrd_load (struct grub_linux_initrd_context *initrd_ctx,
if (initrd_ctx->components[i].newc_name)
{
- ptr += insert_dir (initrd_ctx->components[i].newc_name,
- &root, ptr);
+ grub_size_t dir_size;
+
+ if (insert_dir (initrd_ctx->components[i].newc_name, &root, ptr,
+ &dir_size))
+ {
+ free_dir (root);
+ grub_initrd_close (initrd_ctx);
+ return grub_errno;
+ }
+ ptr += dir_size;
ptr = make_header (ptr, initrd_ctx->components[i].newc_name,
grub_strlen (initrd_ctx->components[i].newc_name),
0100777,
--
2.14.4
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