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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-26 16:22:40 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-03-18 12:24:19 +0100 |
| commit | f490e8aea3f03497efcee81d28fd962d431663c4 (patch) | |
| tree | 52aee1fd270a47eb6afd301ed0a371643d3e1685 /drivers/misc/sgi-gru | |
| parent | d108b132ea39cdcd63a1d6b4460fc4c7d183c7e5 (diff) | |
| download | linux-f490e8aea3f03497efcee81d28fd962d431663c4.tar.gz linux-f490e8aea3f03497efcee81d28fd962d431663c4.tar.bz2 linux-f490e8aea3f03497efcee81d28fd962d431663c4.zip | |
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/sgi-gru')
| -rw-r--r-- | drivers/misc/sgi-gru/grulib.h | 2 | ||||
| -rw-r--r-- | drivers/misc/sgi-gru/grutables.h | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/misc/sgi-gru/grulib.h b/drivers/misc/sgi-gru/grulib.h index e77d1b1f9d05..85c103923632 100644 --- a/drivers/misc/sgi-gru/grulib.h +++ b/drivers/misc/sgi-gru/grulib.h @@ -136,7 +136,7 @@ struct gru_dump_context_header { pid_t pid; unsigned long vaddr; int cch_locked; - unsigned long data[0]; + unsigned long data[]; }; /* diff --git a/drivers/misc/sgi-gru/grutables.h b/drivers/misc/sgi-gru/grutables.h index a7e44b2eb413..5ce8f3081e96 100644 --- a/drivers/misc/sgi-gru/grutables.h +++ b/drivers/misc/sgi-gru/grutables.h @@ -372,7 +372,7 @@ struct gru_thread_state { int ts_data_valid; /* Indicates if ts_gdata has valid data */ struct gru_gseg_statistics ustats; /* User statistics */ - unsigned long ts_gdata[0]; /* save area for GRU data (CB, + unsigned long ts_gdata[]; /* save area for GRU data (CB, DS, CBE) */ }; |