Flexible array members have some restrictions (must be last
in a structure, not in a union) and a number of dangerous or
non-sensical usage (in an array, in nested structure or even
using sizeof() on the containing structure). Sparse currently
supports flexible array members but barely and doesn't help
finding bugs related to them. This series aims at improving this:
* fix structure alignment in the presence of a flexible array member
* issue an error if the flexible array is not last or in a union
* add an option to issue a warning:
* on arrays of such 'flexible structures'
* when using sizeof() on the containing structure
* when declaring nested aggregate types with a flexible array member
* if the flexible array adds some padding to the structure
When used on the kernel (v5.9-rc1) this results in no errors but
the following number of warnings:
90 array of flexible structures
5719 using sizeof on a flexible structure
1909 flexible array member has padding
888 nested flexible arrays
So, to begin with, the corresponding warning flags default to
-Wflexible-array-array
-Wno-flexible-array-nested
-Wno-flexible-array-padding
-Wno-flexible-array-sizeof
Notes: implicit sizeof() on such 'flexible structures' like here
under are not yet checked:
struct s {
...
int flex[];
} *dst, *src;
...
*dst = *src
Luc Van Oostenryck (13):
flex-array: add testcases
flex-array: factor out common part of lay_out_{struct,union}()
flex-array: do not lay out invalid struct members
flex-array: flexible array members have zero size and alignment is OK
flex-array: detect structures with a flexible array member
flex-array: warn on flexible arrays in unions
flex-array: warn if flexible array is not last
flex-array: identify structures with a flexible array member
flex-array: add helper has_flexible_array()
flex-array: warn when using sizeof() on a flexible array
flex-array: warn an arrays containing a flexible array
flex-array: warn on flexible array in nested aggregate types
flex-array: warn when a flexible array member has some padding
evaluate.c | 3 ++
options.c | 8 ++++++
options.h | 4 +++
sparse.1 | 27 ++++++++++++++++++
symbol.c | 50 +++++++++++++++++++++------------
symbol.h | 8 ++++++
validation/flex-array-align.c | 18 ++++++++++++
validation/flex-array-array.c | 15 ++++++++++
validation/flex-array-error.c | 26 +++++++++++++++++
validation/flex-array-nested.c | 29 +++++++++++++++++++
validation/flex-array-padding.c | 21 ++++++++++++++
validation/flex-array-sizeof.c | 18 ++++++++++++
12 files changed, 209 insertions(+), 18 deletions(-)
create mode 100644 validation/flex-array-align.c
create mode 100644 validation/flex-array-array.c
create mode 100644 validation/flex-array-error.c
create mode 100644 validation/flex-array-nested.c
create mode 100644 validation/flex-array-padding.c
create mode 100644 validation/flex-array-sizeof.c
--
2.28.0
