[rtems commit] Fix CID 1461557

[Sebastian Huber]

Module:    rtems
Branch:    master
Commit:    21351a2f79553592ab9157e2595064619cfe88ad
Changeset: http://git.rtems.org/rtems/commit/?id=21351a2f79553592ab9157e2595064619cfe88ad

Author:    David Gibson <david at gibson.dropbear.id.au>
Date:      Tue Jun  8 15:28:55 2021 +1000

Fix CID 1461557

Coverity gets a bit confused by loading fdt_size_dt_strings() and
using it in a memmove().  In fact this is safe because the callers
have verified this information (via FDT_RW_PROBE() in fdt_pack() or
construction in fdt_open_into()).

Passing in strings_size like we already do struct_size seems to get
Coverity to follow what's going on here.

Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

---

 cpukit/dtc/libfdt/fdt_rw.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/cpukit/dtc/libfdt/fdt_rw.c b/cpukit/dtc/libfdt/fdt_rw.c
index 2fbb545..3621d36 100644
--- a/cpukit/dtc/libfdt/fdt_rw.c
+++ b/cpukit/dtc/libfdt/fdt_rw.c
@@ -394,7 +394,9 @@ int fdt_del_node(void *fdt, int nodeoffset)
 }
 
 static void fdt_packblocks_(const char *old, char *new,
-			    int mem_rsv_size, int struct_size)
+			    int mem_rsv_size,
+			    int struct_size,
+			    int strings_size)
 {
 	int mem_rsv_off, struct_off, strings_off;
 
@@ -409,8 +411,7 @@ static void fdt_packblocks_(const char *old, char *new,
 	fdt_set_off_dt_struct(new, struct_off);
 	fdt_set_size_dt_struct(new, struct_size);
 
-	memmove(new + strings_off, old + fdt_off_dt_strings(old),
-		fdt_size_dt_strings(old));
+	memmove(new + strings_off, old + fdt_off_dt_strings(old), strings_size);
 	fdt_set_off_dt_strings(new, strings_off);
 	fdt_set_size_dt_strings(new, fdt_size_dt_strings(old));
 }
@@ -470,7 +471,8 @@ int fdt_open_into(const void *fdt, void *buf, int bufsize)
 			return -FDT_ERR_NOSPACE;
 	}
 
-	fdt_packblocks_(fdt, tmp, mem_rsv_size, struct_size);
+	fdt_packblocks_(fdt, tmp, mem_rsv_size, struct_size,
+			fdt_size_dt_strings(fdt));
 	memmove(buf, tmp, newsize);
 
 	fdt_set_magic(buf, FDT_MAGIC);
@@ -490,7 +492,8 @@ int fdt_pack(void *fdt)
 
 	mem_rsv_size = (fdt_num_mem_rsv(fdt)+1)
 		* sizeof(struct fdt_reserve_entry);
-	fdt_packblocks_(fdt, fdt, mem_rsv_size, fdt_size_dt_struct(fdt));
+	fdt_packblocks_(fdt, fdt, mem_rsv_size, fdt_size_dt_struct(fdt),
+			fdt_size_dt_strings(fdt));
 	fdt_set_totalsize(fdt, fdt_data_size_(fdt));
 
 	return 0;