| Message ID | 20200507185158.GA14116@embeddedor (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
| Series | dm integrity: Replace zero-length array with flexible-array | expand |
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 3df90daba89e..bac110987a65 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -212,7 +212,7 @@ struct crypt_config { struct mutex bio_alloc_lock; u8 *authenc_key; /* space for keys in authenc() format (if used) */ - u8 key[0]; + u8 key[]; }; #define MIN_IOS 64 diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c index 4094c47eca7f..fe39ed31b20d 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -92,7 +92,7 @@ struct journal_entry { } s; __u64 sector; } u; - commit_id_t last_bytes[0]; + commit_id_t last_bytes[]; /* __u8 tag[0]; */ }; diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c index 8ea20b56b4d6..e3d35c6c9f71 100644 --- a/drivers/md/dm-log-writes.c +++ b/drivers/md/dm-log-writes.c @@ -127,7 +127,7 @@ struct pending_block { char *data; u32 datalen; struct list_head list; - struct bio_vec vecs[0]; + struct bio_vec vecs[]; }; struct per_bio_data { diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c index 9a18bef0a5ff..10e8b2fe787b 100644 --- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c @@ -254,7 +254,7 @@ struct raid_set { int mode; } journal_dev; - struct raid_dev dev[0]; + struct raid_dev dev[]; }; static void rs_config_backup(struct raid_set *rs, struct rs_layout *l) diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c index 089aed57e083..2f655d9f4200 100644 --- a/drivers/md/dm-raid1.c +++ b/drivers/md/dm-raid1.c @@ -83,7 +83,7 @@ struct mirror_set { struct work_struct trigger_event; unsigned nr_mirrors; - struct mirror mirror[0]; + struct mirror mirror[]; }; DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(raid1_resync_throttle, diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c index 71417048256a..35d368c418d0 100644 --- a/drivers/md/dm-stats.c +++ b/drivers/md/dm-stats.c @@ -56,7 +56,7 @@ struct dm_stat { size_t percpu_alloc_size; size_t histogram_alloc_size; struct dm_stat_percpu *stat_percpu[NR_CPUS]; - struct dm_stat_shared stat_shared[0]; + struct dm_stat_shared stat_shared[]; }; #define STAT_PRECISE_TIMESTAMPS 1 diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c index fa813c0f993d..151d022b032d 100644 --- a/drivers/md/dm-stripe.c +++ b/drivers/md/dm-stripe.c @@ -41,7 +41,7 @@ struct stripe_c { /* Work struct used for triggering events*/ struct work_struct trigger_event; - struct stripe stripe[0]; + struct stripe stripe[]; }; /* diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c index 8a0f057b8122..bff4c7fa1cd2 100644 --- a/drivers/md/dm-switch.c +++ b/drivers/md/dm-switch.c @@ -53,7 +53,7 @@ struct switch_ctx { /* * Array of dm devices to switch between. */ - struct switch_path path_list[0]; + struct switch_path path_list[]; }; static struct switch_ctx *alloc_switch_ctx(struct dm_target *ti, unsigned nr_paths, diff --git a/drivers/md/persistent-data/dm-btree-internal.h b/drivers/md/persistent-data/dm-btree-internal.h index a240990a7f33..f4e644dd8101 100644 --- a/drivers/md/persistent-data/dm-btree-internal.h +++ b/drivers/md/persistent-data/dm-btree-internal.h @@ -38,7 +38,7 @@ struct node_header { struct btree_node { struct node_header header; - __le64 keys[0]; + __le64 keys[]; } __packed;
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> --- drivers/md/dm-crypt.c | 2 +- drivers/md/dm-integrity.c | 2 +- drivers/md/dm-log-writes.c | 2 +- drivers/md/dm-raid.c | 2 +- drivers/md/dm-raid1.c | 2 +- drivers/md/dm-stats.c | 2 +- drivers/md/dm-stripe.c | 2 +- drivers/md/dm-switch.c | 2 +- drivers/md/persistent-data/dm-btree-internal.h | 2 +- 9 files changed, 9 insertions(+), 9 deletions(-) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel