Subject: Prevent overflow beyond the end of string in wtf_parse1() From: Tatsuya Kinoshita Bug-Debian: https://github.com/tats/w3m/issues/68 Origin: https://anonscm.debian.org/cgit/collab-maint/w3m.git/commit/?id=00433f4ac2645ac6236ea1892b4a93f26a039a84 --- libwc/wtf.c | 44 ++++++++++++++++++++++++++++++++------------ 1 file changed, 32 insertions(+), 12 deletions(-) diff --git a/libwc/wtf.c b/libwc/wtf.c index cdc6cbc..94d95c1 100644 --- a/libwc/wtf.c +++ b/libwc/wtf.c @@ -397,7 +397,7 @@ wtf_parse1(wc_uchar **p) cc.code = *(q++); } else if (*q > 0xa0) { cc.ccs = wtf_gr_ccs; - if (WC_CCS_IS_WIDE(cc.ccs)) { + if (WC_CCS_IS_WIDE(cc.ccs) && *(q+1)) { cc.code = ((wc_uint32)*q << 8) | *(q+1); q += 2; } else @@ -410,27 +410,47 @@ wtf_parse1(wc_uchar **p) case WC_CCS_A_CS942: case WC_CCS_A_PCS: case WC_CCS_A_UNKNOWN: - cc.ccs |= *(q++) & 0x7f; - cc.code = *(q++); + if (*q && *(q+1)) { + cc.ccs |= *(q++) & 0x7f; + cc.code = *(q++); + } else { + cc.ccs = WC_CCS_US_ASCII; + cc.code = (wc_uint32)' '; + } break; case WC_CCS_A_CS94W: case WC_CCS_A_CS96W: case WC_CCS_A_PCSW: - cc.ccs |= *(q++) & 0x7f; - cc.code = ((wc_uint32)*q << 8) | *(q+1); - q += 2; + if (*q && *(q+1) && *(q+2)) { + cc.ccs |= *(q++) & 0x7f; + cc.code = ((wc_uint32)*q << 8) | *(q+1); + q += 2; + } else { + cc.ccs = WC_CCS_US_ASCII; + cc.code = (wc_uint32)' '; + } break; case WC_CCS_A_WCS16: case WC_CCS_A_WCS16W: - cc.ccs |= (*q & 0x7c) >> 2; - cc.code = wtf_to_wcs16(q); - q += 3; + if (*q && *(q+1) && *(q+2)) { + cc.ccs |= (*q & 0x7c) >> 2; + cc.code = wtf_to_wcs16(q); + q += 3; + } else { + cc.ccs = WC_CCS_US_ASCII; + cc.code = (wc_uint32)' '; + } break; case WC_CCS_A_WCS32: case WC_CCS_A_WCS32W: - cc.ccs |= (*q & 0x70) >> 4; - cc.code = wtf_to_wcs32(q); - q += 5; + if (*q && *(q+1) && *(q+2) && *(q+3) && *(q+4)) { + cc.ccs |= (*q & 0x70) >> 4; + cc.code = wtf_to_wcs32(q); + q += 5; + } else { + cc.ccs = WC_CCS_US_ASCII; + cc.code = (wc_uint32)' '; + } break; default: /* case 0: */ -- 2.10.2