From 8d7d7a93d5265468a0019f11d0bcd2e005ce9ebd Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Thu, 7 May 2020 14:02:10 -0500 Subject: prism54: Replace zero-length array with flexible-array 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] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. 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 Signed-off-by: Kalle Valo Link: https://lore.kernel.org/r/20200507190210.GA15375@embeddedor --- drivers/net/wireless/intersil/prism54/isl_oid.h | 8 ++++---- drivers/net/wireless/intersil/prism54/islpci_mgt.h | 2 +- 2 files changed, 5 insertions(+), 5 deletions(-) (limited to 'drivers/net/wireless/intersil') diff --git a/drivers/net/wireless/intersil/prism54/isl_oid.h b/drivers/net/wireless/intersil/prism54/isl_oid.h index 5441c1f9f2fc..1afc2ccf94ca 100644 --- a/drivers/net/wireless/intersil/prism54/isl_oid.h +++ b/drivers/net/wireless/intersil/prism54/isl_oid.h @@ -37,7 +37,7 @@ struct obj_mlmeex { u16 state; u16 code; u16 size; - u8 data[0]; + u8 data[]; } __packed; struct obj_buffer { @@ -68,12 +68,12 @@ struct obj_bss { struct obj_bsslist { u32 nr; - struct obj_bss bsslist[0]; + struct obj_bss bsslist[]; } __packed; struct obj_frequencies { u16 nr; - u16 mhz[0]; + u16 mhz[]; } __packed; struct obj_attachment { @@ -81,7 +81,7 @@ struct obj_attachment { char reserved; short id; short size; - char data[0]; + char data[]; } __packed; /* diff --git a/drivers/net/wireless/intersil/prism54/islpci_mgt.h b/drivers/net/wireless/intersil/prism54/islpci_mgt.h index d6bbbac46b4a..1f87d0aea60c 100644 --- a/drivers/net/wireless/intersil/prism54/islpci_mgt.h +++ b/drivers/net/wireless/intersil/prism54/islpci_mgt.h @@ -99,7 +99,7 @@ struct islpci_mgmtframe { pimfor_header_t *header; /* payload header, points into buf */ void *data; /* payload ex header, points into buf */ struct work_struct ws; /* argument for schedule_work() */ - char buf[0]; /* fragment buffer */ + char buf[]; /* fragment buffer */ }; int -- cgit v1.2.3