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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 22:05:49 +0300
committerDominik Brodowski <linux@dominikbrodowski.net>2020-05-18 11:28:31 +0300
commit06ed6aa56ffac9241e03a24649e8d048f8f1b10c (patch)
tree31cc68ae56ce5e57befdaca9cd891f6843435d13
parentb9bbe6ed63b2b9f2c9ee5cbd0f2c946a2723f4ce (diff)
downloadlinux-06ed6aa56ffac9241e03a24649e8d048f8f1b10c.tar.xz
pcmcia: 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 <gustavoars@kernel.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
-rw-r--r--include/pcmcia/cistpl.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/include/pcmcia/cistpl.h b/include/pcmcia/cistpl.h
index 59a011101e0e..749320cc9aba 100644
--- a/include/pcmcia/cistpl.h
+++ b/include/pcmcia/cistpl.h
@@ -161,7 +161,7 @@ typedef struct cistpl_funcid_t {
typedef struct cistpl_funce_t {
u_char type;
- u_char data[0];
+ u_char data[];
} cistpl_funce_t;
/*======================================================================
@@ -255,7 +255,7 @@ typedef struct cistpl_data_serv_t {
u_char escape;
u_char encrypt;
u_char misc_features;
- u_char ccitt_code[0];
+ u_char ccitt_code[];
} cistpl_data_serv_t;
typedef struct cistpl_fax_serv_t {
@@ -265,7 +265,7 @@ typedef struct cistpl_fax_serv_t {
u_char encrypt;
u_char features_0;
u_char features_1;
- u_char ccitt_code[0];
+ u_char ccitt_code[];
} cistpl_fax_serv_t;
typedef struct cistpl_voice_serv_t {