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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-27 01:22:40 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-03-18 14:24:19 +0300 |
| commit | f490e8aea3f03497efcee81d28fd962d431663c4 (patch) | |
| tree | 52aee1fd270a47eb6afd301ed0a371643d3e1685 /drivers/misc/mei | |
| parent | d108b132ea39cdcd63a1d6b4460fc4c7d183c7e5 (diff) | |
| download | linux-f490e8aea3f03497efcee81d28fd962d431663c4.tar.xz | |
misc: 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>
Acked-by: Dimitri Sivanich <sivanich@hpe.com>
Link: https://lore.kernel.org/r/20200226222240.GA14474@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/misc/mei')
| -rw-r--r-- | drivers/misc/mei/hw.h | 2 | ||||
| -rw-r--r-- | drivers/misc/mei/mei_dev.h | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/misc/mei/hw.h b/drivers/misc/mei/hw.h index 8231b6941adf..b1a8d5ec88b3 100644 --- a/drivers/misc/mei/hw.h +++ b/drivers/misc/mei/hw.h @@ -216,7 +216,7 @@ struct mei_msg_hdr { struct mei_bus_message { u8 hbm_cmd; - u8 data[0]; + u8 data[]; } __packed; /** diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h index 76f8ff5ff974..3a29db07211d 100644 --- a/drivers/misc/mei/mei_dev.h +++ b/drivers/misc/mei/mei_dev.h @@ -533,7 +533,7 @@ struct mei_device { #endif /* CONFIG_DEBUG_FS */ const struct mei_hw_ops *ops; - char hw[0] __aligned(sizeof(void *)); + char hw[] __aligned(sizeof(void *)); }; static inline unsigned long mei_secs_to_jiffies(unsigned long sec) |