[GIT PULL] bootconfig: Fixes for v7.3-rc3

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

Linus,

Bootconfig fixes for v7.3-rc3

- bootconfig: Fix integer overflow and truncation vulnerabilities in size checks
  . tools/bootconfig: Fix integer overflow and truncation in size checks.
    Fix size check bypasses caused by integer overflow and truncation
    when parsing initrd or standalone bootconfig files, preventing
    buffer overflow and out-of-bounds writes in the userspace tool.
  . bootconfig: Fix integer overflow in initrd size check.
    Fix pointer arithmetic wrap-around in get_boot_config_from_initrd()
    when handling crafted huge size values, preventing fatal kernel
    page faults during early boot.


Please pull the latest bootconfig-fixes-v7.3-rc3 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
bootconfig-fixes-v7.3-rc3

Tag SHA1: e4d95ea65a846d314cd9ef7655ad4ba3f7ff01ad
Head SHA1: 7812d6dab0698001e50e8c2f901e17da3eb6f429


Masami Hiramatsu (Google) (2):
      tools/bootconfig: Fix integer overflow and truncation in size checks
      bootconfig: Fix integer overflow in initrd size check

----
 init/main.c             | 25 +++++++++++++++----------
 tools/bootconfig/main.c | 13 ++++++++++++-
 2 files changed, 27 insertions(+), 11 deletions(-)
---------------------------
diff --git a/init/main.c b/init/main.c
index 2613d3f9b3ce..16749bb7a219 100644
--- a/init/main.c
+++ b/init/main.c
@@ -277,7 +277,8 @@ static void * __init get_boot_config_from_initrd(size_t *_size)
 	u8 *hdr;
 	int i;
 
-	if (!initrd_end)
+	if (!initrd_end || initrd_end < initrd_start ||
+	    initrd_end - initrd_start < BOOTCONFIG_MAGIC_LEN + 8)
 		return NULL;
 
 	data = (char *)initrd_end - BOOTCONFIG_MAGIC_LEN;
@@ -294,16 +295,26 @@ static void * __init get_boot_config_from_initrd(size_t *_size)
 
 found:
 	hdr = (u8 *)(data - 8);
+	if ((unsigned long)hdr < initrd_start)
+		return NULL;
+
 	size = get_unaligned_le32(hdr);
 	csum = get_unaligned_le32(hdr + 4);
 
-	data = ((void *)hdr) - size;
-	if ((unsigned long)data < initrd_start) {
-		pr_err("bootconfig size %d is greater than initrd size %ld\n",
+	if (size > XBC_DATA_MAX) {
+		pr_err("bootconfig size %u is greater than max size %d\n",
+			size, XBC_DATA_MAX);
+		return NULL;
+	}
+
+	if (size > ((unsigned long)hdr - initrd_start)) {
+		pr_err("bootconfig size %u is greater than initrd size %lu\n",
 			size, initrd_end - initrd_start);
 		return NULL;
 	}
 
+	data = ((void *)hdr) - size;
+
 	if (xbc_calc_checksum(data, size) != csum) {
 		pr_err("bootconfig checksum failed\n");
 		return NULL;
@@ -394,12 +405,6 @@ static void __init setup_boot_config(void)
 		return;
 	}
 
-	if (size >= XBC_DATA_MAX) {
-		pr_err("bootconfig size %ld greater than max size %d\n",
-			(long)size, XBC_DATA_MAX);
-		return;
-	}
-
 	ret = xbc_init(data, size, &msg, &pos);
 	if (ret < 0) {
 		if (pos < 0)
diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index 7dc9fff9b637..17d971d47f87 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -140,6 +140,9 @@ static int load_xbc_fd(int fd, char **buf, int size)
 {
 	int ret;
 
+	if (size < 0 || size > XBC_DATA_MAX)
+		return -EINVAL;
+
 	*buf = malloc(size + 1);
 	if (!*buf)
 		return -ENOMEM;
@@ -168,6 +171,13 @@ static int load_xbc_file(const char *path, char **buf)
 		return ret;
 	}
 
+	if (stat.st_size > XBC_DATA_MAX) {
+		pr_err("%s size is too big\n", path);
+		ret = -E2BIG;
+		close(fd);
+		return ret;
+	}
+
 	ret = load_xbc_fd(fd, buf, stat.st_size);
 
 	close(fd);
@@ -218,7 +228,8 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	csum = le32toh(csum);
 
 	/* Wrong size error  */
-	if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) {
+	if (size > XBC_DATA_MAX ||
+	    size > stat.st_size - BOOTCONFIG_FOOTER_SIZE) {
 		pr_err("bootconfig size is too big\n");
 		return -E2BIG;
 	}


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>