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| author |   Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-09 15:23:27 -0500 |
|---|---|---|
| committer |   Kees Cook <keescook@chromium.org> | 2020-03-09 14:45:40 -0700 |
| commit | 8128d3aac0ee3420ede34950c9c0ef9ee118bec9 (patch) | |
| tree | 084fe9fe9cec9666c8840e74ed18a15b64b3e001 /fs/pstore | |
| parent | pstore: pstore_ftrace_seq_next should increase position index (diff) | |
| download | wireguard-linux-8128d3aac0ee3420ede34950c9c0ef9ee118bec9.tar.xz wireguard-linux-8128d3aac0ee3420ede34950c9c0ef9ee118bec9.zip | |
pstore/ram: 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")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200309202327.GA8813@embeddedor
Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'fs/pstore')
| -rw-r--r-- | fs/pstore/ram_core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index 1f4d8c06f9be..c917c191e78c 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -34,7 +34,7 @@ struct persistent_ram_buffer { uint32_t sig; atomic_t start; atomic_t size; - uint8_t data[0]; + uint8_t data[]; }; #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */ |