From caa59e66fdf3b7da52282e3b334d6e6ae00f4292 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 5 Mar 2020 15:04:45 +0100 Subject: libfdt: fix undefined behaviour in fdt_splice_() libfdt: fix undefined behaviour in fdt_splice_() Along the lines of commit d0b3ab0a0f46 ("libfdt: Fix undefined behaviour in fdt_offset_ptr()"), fdt_splice_() similarly may not use pointer arithmetic to do overflow checks. (The left side of the checks added by d4c7c25c9ed1 ["libfdt: check for potential overrun in _fdt_splice()"] doesn't really lend itself to similar replacement though.) Signed-off-by: Jan Beulich Message-Id: Signed-off-by: David Gibson --- cpukit/dtc/libfdt/fdt_rw.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'cpukit/dtc/libfdt/fdt_rw.c') diff --git a/cpukit/dtc/libfdt/fdt_rw.c b/cpukit/dtc/libfdt/fdt_rw.c index 13854253ff..524b520c84 100644 --- a/cpukit/dtc/libfdt/fdt_rw.c +++ b/cpukit/dtc/libfdt/fdt_rw.c @@ -46,7 +46,7 @@ static int fdt_rw_probe_(void *fdt) return err_; \ } -static inline int fdt_data_size_(void *fdt) +static inline unsigned int fdt_data_size_(void *fdt) { return fdt_off_dt_strings(fdt) + fdt_size_dt_strings(fdt); } @@ -54,15 +54,16 @@ static inline int fdt_data_size_(void *fdt) static int fdt_splice_(void *fdt, void *splicepoint, int oldlen, int newlen) { char *p = splicepoint; - char *end = (char *)fdt + fdt_data_size_(fdt); + unsigned int dsize = fdt_data_size_(fdt); + size_t soff = p - (char *)fdt; - if (((p + oldlen) < p) || ((p + oldlen) > end)) + if ((oldlen < 0) || (soff + oldlen < soff) || (soff + oldlen > dsize)) return -FDT_ERR_BADOFFSET; - if ((p < (char *)fdt) || ((end - oldlen + newlen) < (char *)fdt)) + if ((p < (char *)fdt) || (dsize + newlen < oldlen)) return -FDT_ERR_BADOFFSET; - if ((end - oldlen + newlen) > ((char *)fdt + fdt_totalsize(fdt))) + if (dsize - oldlen + newlen > fdt_totalsize(fdt)) return -FDT_ERR_NOSPACE; - memmove(p + newlen, p + oldlen, end - p - oldlen); + memmove(p + newlen, p + oldlen, ((char *)fdt + dsize) - (p + oldlen)); return 0; } -- cgit v1.2.3