NFS/flexfiles: Annotate struct nfs4_ff_layout_segment with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct nfs4_ff_layout_segment.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Anna Schumaker <anna@kernel.org>
Cc: linux-nfs@vger.kernel.org
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230915201434.never.346-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.h b/fs/nfs/flexfilelayout/flexfilelayout.h
index 354a031c69b17204b5be9db6d2e0fab682225adb..f84b3fb0dddd80decadf43a9f4dce8f99fe6e513 100644 (file)
--- a/fs/nfs/flexfilelayout/flexfilelayout.h
+++ b/fs/nfs/flexfilelayout/flexfilelayout.h
@@ -99,7 +99,7 @@ struct nfs4_ff_layout_segment {
        u64                             stripe_unit;
        u32                             flags;
        u32                             mirror_array_cnt;
-       struct nfs4_ff_layout_mirror    *mirror_array[];
+       struct nfs4_ff_layout_mirror    *mirror_array[] __counted_by(mirror_array_cnt);
 };
 
 struct nfs4_flexfile_layout {