libfdt: check for potential overrun in _fdt_splice()
This patch catches the conditions where:
- 'splicepoint' is set to a point outside of [ fdt, fdt_totalsize(fdt) )
- 'newlen' is negative, or 'splicepoint' plus 'newlen' results in overflow
Either of these cases can be caused by math which overflows in calling
functions, or by sizes specified through dynamic means.
Signed-off-by: Courtney Cavin <courtney.cavin@sonymobile.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
diff --git a/libfdt/fdt_rw.c b/libfdt/fdt_rw.c
index 70adec6..8be02b1 100644
--- a/libfdt/fdt_rw.c
+++ b/libfdt/fdt_rw.c
@@ -101,6 +101,8 @@
if (((p + oldlen) < p) || ((p + oldlen) > end))
return -FDT_ERR_BADOFFSET;
+ if ((p < (char *)fdt) || ((end - oldlen + newlen) < (char *)fdt))
+ return -FDT_ERR_BADOFFSET;
if ((end - oldlen + newlen) > ((char *)fdt + fdt_totalsize(fdt)))
return -FDT_ERR_NOSPACE;
memmove(p + newlen, p + oldlen, end - p - oldlen);
