From f490e8aea3f03497efcee81d28fd962d431663c4 Mon Sep 17 00:00:00 2001
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Wed, 26 Feb 2020 16:22:40 -0600
Subject: [PATCH] misc: Replace zero-length array with flexible-array member
Git-commit: f490e8aea3f03497efcee81d28fd962d431663c4
Patch-mainline: v5.7-rc1
References: jsc#SLE-13387
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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/misc/mei/hw.h | 2 +-
drivers/misc/mei/mei_dev.h | 2 +-
drivers/misc/sgi-gru/grulib.h | 2 +-
drivers/misc/sgi-gru/grutables.h | 2 +-
4 files changed, 4 insertions(+), 4 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)
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) */
};
--
2.16.4