diff options
| author | David Gibson <david@gibson.dropbear.id.au> | 2016-10-02 17:59:26 -0600 |
|---|---|---|
| committer | Simon Glass <sjg@chromium.org> | 2016-10-13 13:54:10 -0600 |
| commit | 491c7b6f42a8101f1e84cf8e13a0e23b5eca729e (patch) | |
| tree | e823ddccede6edbf22cdffdebac66c63b2b05fec /lib/libfdt | |
| parent | ef47683646516002694729986d19713e49b903e3 (diff) | |
| download | u-boot-imx-491c7b6f42a8101f1e84cf8e13a0e23b5eca729e.zip u-boot-imx-491c7b6f42a8101f1e84cf8e13a0e23b5eca729e.tar.gz u-boot-imx-491c7b6f42a8101f1e84cf8e13a0e23b5eca729e.tar.bz2 | |
libfdt: Fix undefined behaviour in fdt_offset_ptr()
Using pointer arithmetic to generate a pointer outside a known object is,
technically, undefined behaviour in C. Unfortunately, we were using that
in fdt_offset_ptr() to detect overflows.
To fix this we need to do our bounds / overflow checking on the offsets
before constructing pointers from them.
Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'lib/libfdt')
| -rw-r--r-- | lib/libfdt/fdt.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/lib/libfdt/fdt.c b/lib/libfdt/fdt.c index 96017a1..2055734 100644 --- a/lib/libfdt/fdt.c +++ b/lib/libfdt/fdt.c @@ -35,18 +35,19 @@ int fdt_check_header(const void *fdt) const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len) { - const char *p; + unsigned absoffset = offset + fdt_off_dt_struct(fdt); + + if ((absoffset < offset) + || ((absoffset + len) < absoffset) + || (absoffset + len) > fdt_totalsize(fdt)) + return NULL; if (fdt_version(fdt) >= 0x11) if (((offset + len) < offset) || ((offset + len) > fdt_size_dt_struct(fdt))) return NULL; - p = _fdt_offset_ptr(fdt, offset); - - if (p + len < p) - return NULL; - return p; + return _fdt_offset_ptr(fdt, offset); } uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset) |