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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 22:21:47 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2020-05-12 05:26:32 +0300
commit00b42b70ae521e6ccc86ed403e2d101616689bdc (patch)
tree3f3ff3ed8080a312322d9c414fcbb47d13f548aa /include/scsi
parentf9491ed56e3a73aaa27accf4600671611dcf18bd (diff)
downloadlinux-00b42b70ae521e6ccc86ed403e2d101616689bdc.tar.xz
scsi: libsas: 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") Link: https://lore.kernel.org/r/20200507192147.GA16206@embeddedor Reviewed-by: John Garry <john.garry@huawei.com> Reviewed-by: Jason Yan <yanaijie@huawei.com> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'include/scsi')
-rw-r--r--include/scsi/sas.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/include/scsi/sas.h b/include/scsi/sas.h
index a5d8ae49198c..4726c1bbec65 100644
--- a/include/scsi/sas.h
+++ b/include/scsi/sas.h
@@ -324,7 +324,7 @@ struct ssp_response_iu {
__be32 response_data_len;
u8 resp_data[0];
- u8 sense_data[0];
+ u8 sense_data[];
} __attribute__ ((packed));
struct ssp_command_iu {
@@ -346,7 +346,7 @@ struct ssp_command_iu {
u8 add_cdb_len:6;
u8 cdb[16];
- u8 add_cdb[0];
+ u8 add_cdb[];
} __attribute__ ((packed));
struct xfer_rdy_iu {
@@ -555,7 +555,7 @@ struct ssp_response_iu {
__be32 response_data_len;
u8 resp_data[0];
- u8 sense_data[0];
+ u8 sense_data[];
} __attribute__ ((packed));
struct ssp_command_iu {
@@ -577,7 +577,7 @@ struct ssp_command_iu {
u8 _r_c:2;
u8 cdb[16];
- u8 add_cdb[0];
+ u8 add_cdb[];
} __attribute__ ((packed));
struct xfer_rdy_iu {