From 06ccf63da5d8e90e4dff8b741972a9b279b5bf4c Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 23 Mar 2020 19:38:18 -0500 Subject: tpm_eventlog.h: 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 --- include/linux/tpm_eventlog.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/tpm_eventlog.h b/include/linux/tpm_eventlog.h index 131ea1bad458..c253461b1c4e 100644 --- a/include/linux/tpm_eventlog.h +++ b/include/linux/tpm_eventlog.h @@ -28,7 +28,7 @@ struct tcpa_event { u32 event_type; u8 pcr_value[20]; /* SHA1 */ u32 event_size; - u8 event_data[0]; + u8 event_data[]; }; enum tcpa_event_types { @@ -55,7 +55,7 @@ enum tcpa_event_types { struct tcpa_pc_event { u32 event_id; u32 event_size; - u8 event_data[0]; + u8 event_data[]; }; enum tcpa_pc_event_ids { @@ -102,7 +102,7 @@ struct tcg_pcr_event { struct tcg_event_field { u32 event_size; - u8 event[0]; + u8 event[]; } __packed; struct tcg_pcr_event2_head { -- cgit v1.2.3