| Message ID | 20190727155841.GA13586@host (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | randstruct: fix a bug in is_pure_ops_struct() | expand |
On Sun, Jul 28, 2019 at 12:58:41AM +0900, Joonwon Kang wrote: > Before this, there were false negatives in the case where a struct > contains other structs which contain only function pointers because > of unreachable code in is_pure_ops_struct(). Ah, very true. Something like: struct internal { void (*callback)(void); }; struct wrapper { struct internal foo; void (*other_callback)(void); }; would have not been detected as is_pure_ops_struct()? How did you notice this? (Are there cases of this in the kernel?) > Signed-off-by: Joonwon Kang <kjw1627@gmail.com> Applied; thanks! -Kees > --- > scripts/gcc-plugins/randomize_layout_plugin.c | 11 +++++------ > 1 file changed, 5 insertions(+), 6 deletions(-) > > diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c > index 6d5bbd31db7f..a123282a4fcd 100644 > --- a/scripts/gcc-plugins/randomize_layout_plugin.c > +++ b/scripts/gcc-plugins/randomize_layout_plugin.c > @@ -443,13 +443,12 @@ static int is_pure_ops_struct(const_tree node) > if (node == fieldtype) > continue; > > - if (!is_fptr(fieldtype)) > - return 0; > - > - if (code != RECORD_TYPE && code != UNION_TYPE) > - continue; > + if (code == RECORD_TYPE || code == UNION_TYPE) { > + if (!is_pure_ops_struct(fieldtype)) > + return 0; > + } > > - if (!is_pure_ops_struct(fieldtype)) > + if (!is_fptr(fieldtype)) > return 0; > } > > -- > 2.17.1 >
On Tue, Jul 30, 2019 at 10:11:19AM -0700, Kees Cook wrote: > On Sun, Jul 28, 2019 at 12:58:41AM +0900, Joonwon Kang wrote: > > Before this, there were false negatives in the case where a struct > > contains other structs which contain only function pointers because > > of unreachable code in is_pure_ops_struct(). > > Ah, very true. Something like: > > struct internal { > void (*callback)(void); > }; > > struct wrapper { > struct internal foo; > void (*other_callback)(void); > }; > > would have not been detected as is_pure_ops_struct()? > > How did you notice this? (Are there cases of this in the kernel?) When I compiled kernel with allyesconfig, there seemed to be no such cases, but I found the bug just by code review and test. However, I would like to slightly modify this patch and add one more patch. I will send the patch set soon. > > > Signed-off-by: Joonwon Kang <kjw1627@gmail.com> > > Applied; thanks! > > -Kees > > > --- > > scripts/gcc-plugins/randomize_layout_plugin.c | 11 +++++------ > > 1 file changed, 5 insertions(+), 6 deletions(-) > > > > diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c > > index 6d5bbd31db7f..a123282a4fcd 100644 > > --- a/scripts/gcc-plugins/randomize_layout_plugin.c > > +++ b/scripts/gcc-plugins/randomize_layout_plugin.c > > @@ -443,13 +443,12 @@ static int is_pure_ops_struct(const_tree node) > > if (node == fieldtype) > > continue; > > > > - if (!is_fptr(fieldtype)) > > - return 0; > > - > > - if (code != RECORD_TYPE && code != UNION_TYPE) > > - continue; > > + if (code == RECORD_TYPE || code == UNION_TYPE) { > > + if (!is_pure_ops_struct(fieldtype)) > > + return 0; > > + } > > > > - if (!is_pure_ops_struct(fieldtype)) > > + if (!is_fptr(fieldtype)) > > return 0; > > } > > > > -- > > 2.17.1 > > > > -- > Kees Cook
diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c index 6d5bbd31db7f..a123282a4fcd 100644 --- a/scripts/gcc-plugins/randomize_layout_plugin.c +++ b/scripts/gcc-plugins/randomize_layout_plugin.c @@ -443,13 +443,12 @@ static int is_pure_ops_struct(const_tree node) if (node == fieldtype) continue; - if (!is_fptr(fieldtype)) - return 0; - - if (code != RECORD_TYPE && code != UNION_TYPE) - continue; + if (code == RECORD_TYPE || code == UNION_TYPE) { + if (!is_pure_ops_struct(fieldtype)) + return 0; + } - if (!is_pure_ops_struct(fieldtype)) + if (!is_fptr(fieldtype)) return 0; }
Before this, there were false negatives in the case where a struct contains other structs which contain only function pointers because of unreachable code in is_pure_ops_struct(). Signed-off-by: Joonwon Kang <kjw1627@gmail.com> --- scripts/gcc-plugins/randomize_layout_plugin.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)