path: root/include/xen
diff options
authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-02-26 15:26:12 -0600
committerBoris Ostrovsky <boris.ostrovsky@oracle.com>2020-03-05 09:41:58 -0600
commite8dc73c9f9ea554b36093dea23e4ca3b586105d7 (patch)
tree37e43c73b79a30f1ee8ff8abb303bf591c91afc8 /include/xen
parentLinux 5.6-rc3 (diff)
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>
Diffstat (limited to 'include/xen')
1 files changed, 1 insertions, 1 deletions
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 */