[PATCH v2 01/15] efi/libstub: Fix error unwind freeing fdt in allocate_new_fdt_and_exit_boot()

[Jason Gunthorpe]

Sashiko says fdt_addr can point to either an allocated fdt or the fdt from
get_fdt() which is memory owned by FW.

Only the allocated fdt should be freed on the error unwind path. Use a
dedicated variable for the allocation's size so that the free does not get
confused.

Fixes: 4fc8e738ff3e ("efi: libstub: remove DT dependency from generic stub")
Reviewed-by: Jonathan Cameron <jonathan.cameron at oss.qualcomm.com>
Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
---
 drivers/firmware/efi/libstub/fdt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 23b3543d3041b0..f01450b4997546 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -229,6 +229,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(void *handle,
 	u32 desc_ver;
 	efi_status_t status;
 	struct exit_boot_struct priv;
+	unsigned long fdt_size_allocated = 0;
 	unsigned long fdt_addr = 0;
 	unsigned long fdt_size = 0;
 
@@ -251,12 +252,13 @@ efi_status_t allocate_new_fdt_and_exit_boot(void *handle,
 		if (strstr(cmdline_ptr, "dtb="))
 			efi_err("Ignoring DTB from command line.\n");
 	} else {
-		status = efi_load_dtb(image, &fdt_addr, &fdt_size);
+		status = efi_load_dtb(image, &fdt_addr, &fdt_size_allocated);
 
 		if (status != EFI_SUCCESS && status != EFI_NOT_READY) {
 			efi_err("Failed to load device tree!\n");
 			goto fail;
 		}
+		fdt_size = fdt_size_allocated;
 	}
 
 	if (fdt_addr) {
@@ -334,7 +336,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(void *handle,
 	efi_free(MAX_FDT_SIZE, *new_fdt_addr);
 
 fail:
-	efi_free(fdt_size, fdt_addr);
+	efi_free(fdt_size_allocated, fdt_addr);
 	if (!efi_novamap)
 		efi_bs_call(free_pool, priv.runtime_map);
 
-- 
2.43.0