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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-09 19:04:41 +0100 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2020-03-16 15:56:50 +0100 |
| commit | c2d0699c629d30dde3329003baac3b94f1d717e6 (patch) | |
| tree | a3a78a8dd1500be5ece761a94411f2435cd8f189 | |
| parent | ext2: Silence lockdep warning about reclaim under xattr_sem (diff) | |
| download | linux-c2d0699c629d30dde3329003baac3b94f1d717e6.tar.xz linux-c2d0699c629d30dde3329003baac3b94f1d717e6.zip | |
ext2: xattr.h: Replace zero-length array with flexible-array member
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")
Link: https://lore.kernel.org/r/20200309180441.GA2992@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jan Kara <jack@suse.cz>
| -rw-r--r-- | fs/ext2/xattr.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ext2/xattr.h b/fs/ext2/xattr.h index cee888cdc235..16272e6ddcf4 100644 --- a/fs/ext2/xattr.h +++ b/fs/ext2/xattr.h @@ -39,7 +39,7 @@ struct ext2_xattr_entry { __le32 e_value_block; /* disk block attribute is stored on (n/i) */ __le32 e_value_size; /* size of attribute value */ __le32 e_hash; /* hash value of name and value */ - char e_name[0]; /* attribute name */ + char e_name[]; /* attribute name */ }; #define EXT2_XATTR_PAD_BITS 2 |