From 725cbb63263d27e87f5a4f9b73281e7710de53e4 Mon Sep 17 00:00:00 2001 From: Keith Seitz Date: Thu, 25 Apr 2019 13:05:51 -0700 Subject: [PATCH] c++/24367: Infinite recursion of typedef substitution This bug finds another usage where we end up segfaulting while normalizing user input. inspect_type and replace_type recurse, attempting to substitute the "real" symbol name for the typedef name. However, since the both these names are the same, they keep calling each other until the stack overflows. A simple reproducer for it is given by typedef struct foo foo; int qux (foo *f) { return 0; } (gdb) b qux(foo*) Segmentation fault inspect_type already contains some special handling to prevent a similar situation from occurring with namespaces. I wonder, however, whether we need be so pedantic about the exact nature of the substitution. This patch implements this rather more aggressive assumption that these substitutions should be avoided whenever the replacement symbol's name is exactly the same as the one we're trying to substitute. [In the above example, we're trying to substitute the tyepdef named "foo" with the symbol named "foo" (a struct).] gdb/ChangeLog: PR c++/24367 * cp-support.c (inspect_type): Don't attempt substitutions of symbol with the same name. gdb/testsuite/ChangeLog: PR c++/24367 * gdb.cp/meth-typedefs.cc (incomplete_struct) (another_incomplete_struct, test_incomplete): New definitions. (main): Use new definitions. * gdb.cp/meth-typedefs.exp: Add new tests for `test_incomplete' functions. --- gdb/ChangeLog | 6 ++++++ gdb/cp-support.c | 16 +++++++++++++--- gdb/testsuite/ChangeLog | 9 +++++++++ gdb/testsuite/gdb.cp/meth-typedefs.cc | 13 +++++++++++++ gdb/testsuite/gdb.cp/meth-typedefs.exp | 5 +++++ 5 files changed, 46 insertions(+), 3 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 17e10e8..e0120e7 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2019-04-25 Keith Seitz + + PR c++/24367 + * cp-support.c (inspect_type): Don't attempt substitutions + of symbol with the same name. + 2019-04-25 Tom Tromey PR gdb/24475: diff --git a/gdb/cp-support.c b/gdb/cp-support.c index d02a01d..4afb79a 100644 --- a/gdb/cp-support.c +++ b/gdb/cp-support.c @@ -190,10 +190,20 @@ inspect_type (struct demangle_parse_info *info, /* Get the real type of the typedef. */ type = check_typedef (otype); - /* If the symbol is a namespace and its type name is no different + /* If the symbol name is the same as the original type name, + don't substitute. That would cause infinite recursion in + symbol lookups, as the typedef symbol is often the first + found symbol in the symbol table. + + However, this can happen in a number of situations, such as: + + If the symbol is a namespace and its type name is no different than the name we looked up, this symbol is not a namespace - alias and does not need to be substituted. */ - if (TYPE_CODE (otype) == TYPE_CODE_NAMESPACE + alias and does not need to be substituted. + + If the symbol is typedef and its type name is the same + as the symbol's name, e.g., "typedef struct foo foo;". */ + if (TYPE_NAME (type) != nullptr && strcmp (TYPE_NAME (type), name) == 0) return 0; diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index c81d841..9b0725a 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,12 @@ +2019-04-25 Keith Seitz + + PR c++/24367 + * gdb.cp/meth-typedefs.cc (incomplete_struct) + (another_incomplete_struct, test_incomplete): New definitions. + (main): Use new definitions. + * gdb.cp/meth-typedefs.exp: Add new tests for `test_incomplete' + functions. + 2019-04-25 Sergio Durigan Junior PR corefiles/11608 diff --git a/gdb/testsuite/gdb.cp/meth-typedefs.cc b/gdb/testsuite/gdb.cp/meth-typedefs.cc index 0c4d095..f65478e 100644 --- a/gdb/testsuite/gdb.cp/meth-typedefs.cc +++ b/gdb/testsuite/gdb.cp/meth-typedefs.cc @@ -36,6 +36,13 @@ typedef void (*fptr2) (fptr1, my_other_type_2); typedef void (*fptr3) (fptr2, my_other_type); typedef void (*fptr4) (anon_enum a, anon_struct const& b, anon_union const*** c); +// For c++/24367 testing +typedef struct incomplete_struct incomplete_struct; +typedef struct _incomplete_struct another_incomplete_struct; +int test_incomplete (incomplete_struct *p) { return 0; } // test_incomplete(incomplete_struct*) +int test_incomplete (another_incomplete_struct *p) { return 1; } // test_incomplete(another_incomplete_struct*) +int test_incomplete (int *p) { return -1; } // test_incomplete(int*) + namespace A { class foo @@ -147,5 +154,11 @@ main (void) fptr4 f4; + // Tests for c++/24367 + int *i = nullptr; + incomplete_struct *is = nullptr; + another_incomplete_struct *ais = nullptr; + int result = (test_incomplete (i) + test_incomplete (is) + + test_incomplete (ais)); return 0; } diff --git a/gdb/testsuite/gdb.cp/meth-typedefs.exp b/gdb/testsuite/gdb.cp/meth-typedefs.exp index b9c383b..76a8fc9 100644 --- a/gdb/testsuite/gdb.cp/meth-typedefs.exp +++ b/gdb/testsuite/gdb.cp/meth-typedefs.exp @@ -137,6 +137,11 @@ foreach t $typedefs(_BAR_) { add methods "test" "$t&" {_BAR_&} } +# Tests for c++/24367 +foreach t {int incomplete_struct another_incomplete_struct} { + add methods "test_incomplete" "${t}*" [string_to_regexp "${t}*"] +} + gdb_test_no_output "set listsize 1" "" # Finally, for each method in the list METHODS, check whether -- 2.7.4