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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 13:52:30 -0500 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2020-05-08 10:38:12 +0200 |
| commit | 374ad001f762e4e4c736c5e2455e9949555459ab (patch) | |
| tree | b2253938c38e90b61557a90f93ed3378a936d6ce /fs/notify | |
| parent | 7b26aa243d3c4d9a564e87c17dc4317a67727335 (diff) | |
| download | linux-374ad001f762e4e4c736c5e2455e9949555459ab.tar.bz2 | |
fanotify: Replace zero-length array with flexible-array
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.
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")
Link: https://lore.kernel.org/r/20200507185230.GA14229@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/notify')
| -rw-r--r-- | fs/notify/fanotify/fanotify.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h index 35bfbf4a7aac..8ce7ccfc4b0d 100644 --- a/fs/notify/fanotify/fanotify.h +++ b/fs/notify/fanotify/fanotify.h @@ -89,7 +89,7 @@ struct fanotify_name_event { __kernel_fsid_t fsid; struct fanotify_fh dir_fh; u8 name_len; - char name[0]; + char name[]; }; static inline struct fanotify_name_event * |