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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-26 22:26:12 +0100 |
|---|---|---|
| committer | Boris Ostrovsky <boris.ostrovsky@oracle.com> | 2020-03-05 16:41:58 +0100 |
| commit | e8dc73c9f9ea554b36093dea23e4ca3b586105d7 (patch) | |
| tree | 37e43c73b79a30f1ee8ff8abb303bf591c91afc8 | |
| parent | Linux 5.6-rc3 (diff) | |
| download | linux-e8dc73c9f9ea554b36093dea23e4ca3b586105d7.tar.xz linux-e8dc73c9f9ea554b36093dea23e4ca3b586105d7.zip | |
xen: 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/20200226212612.GA4663@embeddedor
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
| -rw-r--r-- | drivers/xen/xen-pciback/pciback.h | 2 | ||||
| -rw-r--r-- | include/xen/interface/io/tpmif.h | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h index ce1077e32466..7c95516a860f 100644 --- a/drivers/xen/xen-pciback/pciback.h +++ b/drivers/xen/xen-pciback/pciback.h @@ -52,7 +52,7 @@ struct xen_pcibk_dev_data { unsigned int ack_intr:1; /* .. and ACK-ing */ unsigned long handled; unsigned int irq; /* Saved in case device transitions to MSI/MSI-X */ - char irq_name[0]; /* xen-pcibk[000:04:00.0] */ + char irq_name[]; /* xen-pcibk[000:04:00.0] */ }; /* Used by XenBus and xen_pcibk_ops.c */ diff --git a/include/xen/interface/io/tpmif.h b/include/xen/interface/io/tpmif.h index 28e7dcd75e82..f8aa8bac5196 100644 --- a/include/xen/interface/io/tpmif.h +++ b/include/xen/interface/io/tpmif.h @@ -46,7 +46,7 @@ struct vtpm_shared_page { uint8_t pad; uint8_t nr_extra_pages; /* extra pages for long packets; may be zero */ - uint32_t extra_pages[0]; /* grant IDs; length in nr_extra_pages */ + uint32_t extra_pages[]; /* grant IDs; length in nr_extra_pages */ }; #endif |