From 652eb801d2141b57dca3215e71c55e8356b407a2 Mon Sep 17 00:00:00 2001 From: Xi Wang Date: Fri, 10 May 2013 17:00:35 -0400 Subject: [PATCH] fix SIGFPE caused by signed division overflow Avoid evaluating INT_MIN / -1 and INT_MIN % -1, which will trap on x86 and crash sparse. Signed-off-by: Xi Wang Signed-off-by: Christopher Li --- expand.c | 2 ++ simplify.c | 4 ++++ validation/div.c | 29 +++++++++++++++++++++++++++++ 3 files changed, 35 insertions(+) create mode 100644 validation/div.c diff --git a/expand.c b/expand.c index effd27b5..2dfa5e5f 100644 --- a/expand.c +++ b/expand.c @@ -239,6 +239,8 @@ static int simplify_int_binop(struct expression *expr, struct symbol *ctype) case SIGNED('%'): if (!r) goto Div; + if (l == mask && sr == -1) + goto Overflow; v = sl % sr; break; diff --git a/simplify.c b/simplify.c index bda4a5b4..b5cd0ea7 100644 --- a/simplify.c +++ b/simplify.c @@ -406,6 +406,8 @@ static int simplify_constant_binop(struct instruction *insn) case OP_DIVS: if (!right) return 0; + if (left == mask && right == -1) + return 0; res = left / right; break; case OP_MODU: @@ -416,6 +418,8 @@ static int simplify_constant_binop(struct instruction *insn) case OP_MODS: if (!right) return 0; + if (left == mask && right == -1) + return 0; res = left % right; break; case OP_SHL: diff --git a/validation/div.c b/validation/div.c new file mode 100644 index 00000000..3dcbfd57 --- /dev/null +++ b/validation/div.c @@ -0,0 +1,29 @@ +#include + +static int xd = 1 / 0; +static int xl = 1L / 0; +static int xll = 1LL / 0; + +static int yd = INT_MIN / -1; +static long yl = LONG_MIN / -1; +static long long yll = LLONG_MIN / -1; + +static int zd = INT_MIN % -1; +static long zl = LONG_MIN % -1; +static long long zll = LLONG_MIN % -1; + +/* + * check-name: division constants + * + * check-error-start +div.c:3:19: warning: division by zero +div.c:4:20: warning: division by zero +div.c:5:22: warning: division by zero +div.c:7:25: warning: constant integer operation overflow +div.c:8:27: warning: constant integer operation overflow +div.c:9:34: warning: constant integer operation overflow +div.c:11:25: warning: constant integer operation overflow +div.c:12:27: warning: constant integer operation overflow +div.c:13:34: warning: constant integer operation overflow + * check-error-end + */ -- 2.11.4.GIT