bootutil: swap_scratch: Fix scratch scrambling

nordic-mik7 · nordic-mik7 · commit 56aad5101c8a · 2025-08-08T16:42:15.000+02:00
This commit fixes the scrambling of the scratch area after
persisting a trailer to the primary slot. Previous use of
boot_erase_region() didn't guarantee that the scratch area is
scrambled, as it only erases memory for devices that selects
CONFIG_MCUBOOT_STORAGE_WITH_ERASE.

Signed-off-by: Michal Kozikowski &lt;michal.kozikowski@nordicsemi.no&gt;
diff --git a/boot/bootutil/src/swap_scratch.c b/boot/bootutil/src/swap_scratch.c
@@ -913,7 +913,7 @@ boot_swap_sectors(int idx, uint32_t sz, struct boot_loader_state *state,
             * happens then the scratch which is partially erased would be wrote back to the
             * primary slot, causing a corrupt unbootable image
             */
-            rc = boot_erase_region(fap_scratch, 0, flash_area_get_size(fap_scratch), true);
+            rc = boot_scramble_region(fap_scratch, 0, flash_area_get_size(fap_scratch), true);
             assert(rc == 0);
         }
     }

Original file line number	Diff line number	Diff line change
`@@ -913,7 +913,7 @@ boot_swap_sectors(int idx, uint32_t sz, struct boot_loader_state *state,`
`913`	`913`	`* happens then the scratch which is partially erased would be wrote back to the`
`914`	`914`	`* primary slot, causing a corrupt unbootable image`
`915`	`915`	`*/`
`916`		`- rc = boot_erase_region(fap_scratch, 0, flash_area_get_size(fap_scratch), true);`
	`916`	`+ rc = boot_scramble_region(fap_scratch, 0, flash_area_get_size(fap_scratch), true);`
`917`	`917`	`assert(rc == 0);`
`918`	`918`	`}`
`919`	`919`	`}`