@@ -97,7 +97,7 @@ u64 select_estimate_accuracy(struct timespec64 *tv)
struct poll_table_page {
struct poll_table_page * next;
struct poll_table_entry * entry;
- struct poll_table_entry entries[0];
+ struct poll_table_entry entries[];
};
#define POLL_TABLE_FULL(table) \
@@ -826,7 +826,7 @@ SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)
struct poll_list {
struct poll_list *next;
int len;
- struct pollfd entries[0];
+ struct pollfd entries[];
};
#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
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] This issue was found with the help of Coccinelle. [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 <gustavo@embeddedor.com> --- fs/select.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)