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nfs41: pnfs: filelayout: Replace one-element array with flexible-array member

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There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

Refactor the code a bit according to the use of a flexible-array member
in struct nfs4_file_layout_dsaddr instead of a one-element array, and
use the struct_size() helper.

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

This issue was found with the help of Coccinelle and audited and fixed,
manually.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Gustavo A. R. Silva
2021-08-10 18:31:01 -05:00
committed by Anna Schumaker
parent 4b0c359b81
commit c72a826829
2 changed files with 2 additions and 4 deletions
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2
fs/nfs/filelayout/filelayout.h
View File

@@ -51,7 +51,7 @@ struct nfs4_file_layout_dsaddr {
u32 stripe_count; u32 stripe_count;
u8 *stripe_indices; u8 *stripe_indices;
u32 ds_num; u32 ds_num;
struct nfs4_pnfs_ds *ds_list[1]; struct nfs4_pnfs_ds *ds_list[];
}; };
struct nfs4_filelayout_segment { struct nfs4_filelayout_segment {

4
fs/nfs/filelayout/filelayoutdev.c
View File

@@ -136,9 +136,7 @@ nfs4_fl_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
goto out_err_free_stripe_indices; goto out_err_free_stripe_indices;
} }
dsaddr = kzalloc(sizeof(*dsaddr) + dsaddr = kzalloc(struct_size(dsaddr, ds_list, num), gfp_flags);
(sizeof(struct nfs4_pnfs_ds *) * (num - 1)),
gfp_flags);
if (!dsaddr) if (!dsaddr)
goto out_err_free_stripe_indices; goto out_err_free_stripe_indices;