[PATCH] bootstd: Avoid freeing a non-allocated buffer

[Simon Glass]

EFI applications can be very large and thus used to cause boot failures
when malloc() space was exhausted.

A recent changed fixed this by using the kernel_addr_r environment var
as the address of the buffer. However, it still frees the buffer when
the bootflow is discarded.

Fix this by introducing a flag to indicate whether the buffer was
allocated, or not.

Note that kernel_addr_r is not the last word here. It might be better
to use lmb to place images. But there is a lot of refactoring to do
before we can remove the environment variables. The distro scripts rely
on them so it is safe for bootstd to do so too.

Fixes: 6a8c2f9781c bootstd: Avoid allocating memory for the EFI file

Signed-off-by: Simon Glass <sjg at chromium.org>
Reported by: Simon Glass <sjg at chromium.org>
Reported by: Shantur Rathore <i at shantur.com>
---

 boot/bootflow.c     | 3 ++-
 boot/bootmeth_efi.c | 1 +
 include/bootflow.h  | 5 ++++-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/boot/bootflow.c b/boot/bootflow.c
index 6922e7e0c4e7..1ea2966ae9a5 100644
--- a/boot/bootflow.c
+++ b/boot/bootflow.c
@@ -467,7 +467,8 @@ void bootflow_free(struct bootflow *bflow)
 	free(bflow->name);
 	free(bflow->subdir);
 	free(bflow->fname);
-	free(bflow->buf);
+	if (!(bflow->flags & BOOTFLOWF_STATIC_BUF))
+		free(bflow->buf);
 	free(bflow->os_name);
 	free(bflow->fdt_fname);
 	free(bflow->bootmeth_priv);
diff --git a/boot/bootmeth_efi.c b/boot/bootmeth_efi.c
index ae936c8daa18..9ba7734911e1 100644
--- a/boot/bootmeth_efi.c
+++ b/boot/bootmeth_efi.c
@@ -160,6 +160,7 @@ static int efiload_read_file(struct bootflow *bflow, ulong addr)
 	if (ret)
 		return log_msg_ret("read", ret);
 	bflow->buf = map_sysmem(addr, bflow->size);
+	bflow->flags |= BOOTFLOWF_STATIC_BUF;
 
 	set_efi_bootdev(desc, bflow);
 
diff --git a/include/bootflow.h b/include/bootflow.h
index 44d3741eacae..fede8f22a2b8 100644
--- a/include/bootflow.h
+++ b/include/bootflow.h
@@ -43,9 +43,12 @@ enum bootflow_state_t {
  *	and it is using the prior-stage FDT, which is the U-Boot control FDT.
  *	This is only possible with the EFI bootmeth (distro-efi) and only when
  *	CONFIG_OF_HAS_PRIOR_STAGE is enabled
+ * @BOOTFLOWF_STATIC_BUF: Indicates that @bflow->buf is statically set, rather
+ *	than being allocated by malloc().
  */
 enum bootflow_flags_t {
 	BOOTFLOWF_USE_PRIOR_FDT	= 1 << 0,
+	BOOTFLOWF_STATIC_BUF	= 1 << 1,
 };
 
 /**
@@ -72,7 +75,7 @@ enum bootflow_flags_t {
  * @fname: Filename of bootflow file (allocated)
  * @logo: Logo to display for this bootflow (BMP format)
  * @logo_size: Size of the logo in bytes
- * @buf: Bootflow file contents (allocated)
+ * @buf: Bootflow file contents (allocated unless @flags & BOOTFLOWF_STATIC_BUF)
  * @size: Size of bootflow file in bytes
  * @err: Error number received (0 if OK)
  * @os_name: Name of the OS / distro being booted, or NULL if not known
-- 
2.43.0.rc0.421.g78406f8d94-goog