We are failing to detect accessing a null pointer in &s->i because v_3 = &s_2->i; is not gimple_assign_load_p: 1997 if (flag_sanitize & (SANITIZE_NULL | SANITIZE_ALIGNMENT)) 1998 { 1999 if (gimple_store_p (stmt)) 2000 instrument_null (gsi, true); 2001 if (gimple_assign_load_p (stmt)) 2002 instrument_null (gsi, false); 2003 }
So I think we can use gimple_assign_single_p instead of gimple_assign_load_p and then strip the ADDR_EXPR in instrument_null before getting its base address. (I've seen stripping ADDR_EXPR before get_base_address elsewhere in the codebase, too.) Bootstrapped-ubsan/regtested on x86_64-linux, ok for trunk? 2017-05-17 Marek Polacek <pola...@redhat.com> PR sanitizer/80797 * ubsan.c (instrument_null): Unwrap ADDR_EXPRs. (pass_ubsan::execute): Call gimple_assign_single_p instead of gimple_assign_load_p. * c-c++-common/ubsan/null-12.c: New test. diff --git gcc/testsuite/c-c++-common/ubsan/null-12.c gcc/testsuite/c-c++-common/ubsan/null-12.c index e69de29..3478dc1 100644 --- gcc/testsuite/c-c++-common/ubsan/null-12.c +++ gcc/testsuite/c-c++-common/ubsan/null-12.c @@ -0,0 +1,42 @@ +/* PR sanitizer/80797 */ +/* { dg-do run } */ +/* { dg-options "-fsanitize=undefined" } */ + +struct S +{ + int i; +}; + +struct R +{ + struct T { + int i; + } *t; +} r; + +int +main () +{ + struct S *s = 0; + struct S *s2[1] = { }; + + int *v1 = &s->i; + int *v2 = &(*s).i; + int *v3 = &s2[0]->i; + int *v4 = &s->i + 1; + int *v5 = &r.t->i; + + asm ("" : : "r" (&v1) : "memory"); + asm ("" : : "r" (&v2) : "memory"); + asm ("" : : "r" (&v3) : "memory"); + asm ("" : : "r" (&v4) : "memory"); + asm ("" : : "r" (&v5) : "memory"); + + return 0; +} + +/* { dg-output "member access within null pointer of type 'struct S'\[^\n\r]*(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*member access within null pointer of type 'struct S'\[^\n\r]*(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*member access within null pointer of type 'struct S'\[^\n\r]*(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*member access within null pointer of type 'struct S'\[^\n\r]*(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*member access within null pointer of type 'struct T'" } */ diff --git gcc/ubsan.c gcc/ubsan.c index 4159cc5..a4808d2 100644 --- gcc/ubsan.c +++ gcc/ubsan.c @@ -1208,6 +1208,9 @@ instrument_null (gimple_stmt_iterator gsi, bool is_lhs) { gimple *stmt = gsi_stmt (gsi); tree t = is_lhs ? gimple_get_lhs (stmt) : gimple_assign_rhs1 (stmt); + /* Handle also e.g. &s->i. */ + if (TREE_CODE (t) == ADDR_EXPR) + t = TREE_OPERAND (t, 0); tree base = get_base_address (t); const enum tree_code code = TREE_CODE (base); if (code == MEM_REF @@ -1998,7 +2001,7 @@ pass_ubsan::execute (function *fun) { if (gimple_store_p (stmt)) instrument_null (gsi, true); - if (gimple_assign_load_p (stmt)) + if (gimple_assign_single_p (stmt)) instrument_null (gsi, false); } Marek