[PATCH v2] bootstage: Fix out-of-bounds read in reloc_bootstage()

[Richard Weinberger]

bootstage_get_size() returns the total size of the data structure
including associated records.
When copying from gd->bootstage, only the allocation size of gd->bootstage
must be used. Otherwise too much memory is copied.

This bug caused no harm so far because gd->new_bootstage is always
large enough and reading beyond the allocation length of gd->bootstage
caused no problem due to the U-Boot memory layout.

Fix by using the correct size and perform the initial copy directly
in bootstage_relocate() to have the whole relocation process in the
same function.

Signed-off-by: Richard Weinberger <richard at nod.at>
---
Changes since v1:
- Pass gd->new_bootstage to bootstage_relocate()
---
 common/board_f.c    | 8 +-------
 common/bootstage.c  | 8 ++++++--
 include/bootstage.h | 4 ++--
 3 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/common/board_f.c b/common/board_f.c
index 29e185137a..21a8944e2b 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -683,13 +683,7 @@ static int reloc_bootstage(void)
 	if (gd->flags & GD_FLG_SKIP_RELOC)
 		return 0;
 	if (gd->new_bootstage) {
-		int size = bootstage_get_size();
-
-		debug("Copying bootstage from %p to %p, size %x\n",
-		      gd->bootstage, gd->new_bootstage, size);
-		memcpy(gd->new_bootstage, gd->bootstage, size);
-		gd->bootstage = gd->new_bootstage;
-		bootstage_relocate();
+		bootstage_relocate(gd->new_bootstage);
 	}
 #endif
 
diff --git a/common/bootstage.c b/common/bootstage.c
index b6c268d9f4..49acc9078a 100644
--- a/common/bootstage.c
+++ b/common/bootstage.c
@@ -54,12 +54,16 @@ struct bootstage_hdr {
 	u32 next_id;		/* Next ID to use for bootstage */
 };
 
-int bootstage_relocate(void)
+int bootstage_relocate(void *to)
 {
-	struct bootstage_data *data = gd->bootstage;
+	struct bootstage_data *data;
 	int i;
 	char *ptr;
 
+	debug("Copying bootstage from %p to %p\n", gd->bootstage, to);
+	memcpy(to, gd->bootstage, sizeof(struct bootstage_data));
+	data = gd->bootstage = to;
+
 	/* Figure out where to relocate the strings to */
 	ptr = (char *)(data + 1);
 
diff --git a/include/bootstage.h b/include/bootstage.h
index f4e77b09d7..57792648c4 100644
--- a/include/bootstage.h
+++ b/include/bootstage.h
@@ -258,7 +258,7 @@ void show_boot_progress(int val);
  * relocation, since memory can be overwritten later.
  * Return: Always returns 0, to indicate success
  */
-int bootstage_relocate(void);
+int bootstage_relocate(void *to);
 
 /**
  * Add a new bootstage record
@@ -395,7 +395,7 @@ static inline ulong bootstage_add_record(enum bootstage_id id,
  * and won't even do that unless CONFIG_SHOW_BOOT_PROGRESS is defined
  */
 
-static inline int bootstage_relocate(void)
+static inline int bootstage_relocate(void *to)
 {
 	return 0;
 }
-- 
2.35.3