@@ -622,7 +622,8 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
rsv = (void *)(p + prsv % PAGE_SIZE);
/* reserve the entry itself */
- memblock_reserve(prsv, EFI_MEMRESERVE_SIZE(rsv->size));
+ memblock_reserve(prsv,
+ struct_size(rsv, entry, rsv->size));
for (i = 0; i < atomic_read(&rsv->count); i++) {
memblock_reserve(rsv->entry[i].base,
@@ -1234,14 +1234,11 @@ struct linux_efi_memreserve {
struct {
phys_addr_t base;
phys_addr_t size;
- } entry[0];
+ } entry[];
};
-#define EFI_MEMRESERVE_SIZE(count) (sizeof(struct linux_efi_memreserve) + \
- (count) * sizeof(((struct linux_efi_memreserve *)0)->entry[0]))
-
#define EFI_MEMRESERVE_COUNT(size) (((size) - sizeof(struct linux_efi_memreserve)) \
- / sizeof(((struct linux_efi_memreserve *)0)->entry[0]))
+ / sizeof_field(struct linux_efi_memreserve, entry[0]))
void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size);
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. Lastly, make use of the sizeof_field() helper instead of an open-coded version. This issue was found with the help of Coccinelle and audited _manually_. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- drivers/firmware/efi/efi.c | 3 ++- include/linux/efi.h | 7 ++----- 2 files changed, 4 insertions(+), 6 deletions(-)