https://github.com/torvalds/linux
Revision f36aaf8be421099103193c49796a14213d3be315 authored by Gustavo A. R. Silva on 23 March 2020, 21:43:39 UTC, committed by Gustavo A. R. Silva on 18 April 2020, 20:44:54 UTC
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>
1 parent 0a368bf
History
Tip revision: f36aaf8be421099103193c49796a14213d3be315 authored by Gustavo A. R. Silva on 23 March 2020, 21:43:39 UTC
blk-mq: Replace zero-length array with flexible-array member
Tip revision: f36aaf8
File Mode Size
apparmor
bpf
integrity
keys
loadpin
lockdown
safesetid
selinux
smack
tomoyo
yama
Kconfig -rw-r--r-- 10.7 KB
Kconfig.hardening -rw-r--r-- 7.9 KB
Makefile -rw-r--r-- 1.3 KB
commoncap.c -rw-r--r-- 38.9 KB
device_cgroup.c -rw-r--r-- 20.8 KB
inode.c -rw-r--r-- 10.6 KB
lsm_audit.c -rw-r--r-- 10.7 KB
min_addr.c -rw-r--r-- 1.3 KB
security.c -rw-r--r-- 61.8 KB

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