From 9ccffd1298b5235b25ad05b89e3104fb2935fe27 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 27 Nov 2020 22:40:01 +0000 Subject: [PATCH] preprocessor: Fix #line overflow check [PR97602] The preprocessor check for overflow (of linenum_type = unsigned int) when reading the line number in a #line directive is incomplete; it checks "reg < reg_prev" which doesn't cover all cases where multiplying by 10 overflowed. Fix this by checking for overflow before rather than after it occurs (using essentially the same logic as used by e.g. glibc printf when reading width and precision values from strings). Bootstrapped with no regressions for x86_64-pc-linux-gnu. libcpp/ 2020-11-27 Joseph Myers PR preprocessor/97602 * directives.c (strtolinenum): Check for overflow before it occurs. Correct comment. gcc/testsuite/ 2020-11-27 Joseph Myers PR preprocessor/97602 * gcc.dg/cpp/line9.c, gcc.dg/cpp/line10.c: New tests. --- gcc/testsuite/gcc.dg/cpp/line10.c | 5 +++++ gcc/testsuite/gcc.dg/cpp/line9.c | 5 +++++ libcpp/directives.c | 10 +++++----- 3 files changed, 15 insertions(+), 5 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/cpp/line10.c create mode 100644 gcc/testsuite/gcc.dg/cpp/line9.c diff --git a/gcc/testsuite/gcc.dg/cpp/line10.c b/gcc/testsuite/gcc.dg/cpp/line10.c new file mode 100644 index 0000000..9f5f079 --- /dev/null +++ b/gcc/testsuite/gcc.dg/cpp/line10.c @@ -0,0 +1,5 @@ +/* Test #line overflow checks: bug 97602. */ +/* { dg-do preprocess } */ +/* { dg-options "-pedantic" } */ + +#line 4294967296 /* { dg-warning "line number out of range" } */ diff --git a/gcc/testsuite/gcc.dg/cpp/line9.c b/gcc/testsuite/gcc.dg/cpp/line9.c new file mode 100644 index 0000000..8060aff --- /dev/null +++ b/gcc/testsuite/gcc.dg/cpp/line9.c @@ -0,0 +1,5 @@ +/* Test #line overflow checks: bug 97602. */ +/* { dg-do preprocess } */ +/* { dg-options "-pedantic" } */ + +#line 5000000000 /* { dg-warning "line number out of range" } */ diff --git a/libcpp/directives.c b/libcpp/directives.c index fa66b5c..7511560 100644 --- a/libcpp/directives.c +++ b/libcpp/directives.c @@ -915,12 +915,11 @@ read_flag (cpp_reader *pfile, unsigned int last) /* Subroutine of do_line and do_linemarker. Convert a number in STR, of length LEN, to binary; store it in NUMP, and return false if the number was well-formed, true if not. WRAPPED is set to true if the - number did not fit into 'unsigned long'. */ + number did not fit into 'linenum_type'. */ static bool strtolinenum (const uchar *str, size_t len, linenum_type *nump, bool *wrapped) { linenum_type reg = 0; - linenum_type reg_prev = 0; uchar c; *wrapped = false; @@ -929,11 +928,12 @@ strtolinenum (const uchar *str, size_t len, linenum_type *nump, bool *wrapped) c = *str++; if (!ISDIGIT (c)) return true; + if (reg > ((linenum_type) -1) / 10) + *wrapped = true; reg *= 10; - reg += c - '0'; - if (reg < reg_prev) + if (reg > ((linenum_type) -1) - (c - '0')) *wrapped = true; - reg_prev = reg; + reg += c - '0'; } *nump = reg; return false; -- 2.7.4