From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: linux-hardening@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>
Subject: [PATCH 1/3][next] lib/stackdepot.c: Replace one-element array with flexible-array member
Date: Thu, 1 Oct 2020 10:25:08 -0500 [thread overview]
Message-ID: <2f1e6a17aaa891ad9c58817cf0a10b8ab8894f59.1601565471.git.gustavoars@kernel.org> (raw)
In-Reply-To: <cover.1601565471.git.gustavoars@kernel.org>
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 according to the use of a flexible-array member in
struct stack_record, instead of a one-element array, and use the
struct_size() helper to calculate the size for the allocation.
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/5f75876b.x9zdN10esiC0qLHV%25lkp@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
lib/stackdepot.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 2caffc64e4c8..c6106cfb7950 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -62,7 +62,7 @@ struct stack_record {
u32 hash; /* Hash in the hastable */
u32 size; /* Number of frames in the stack */
union handle_parts handle;
- unsigned long entries[1]; /* Variable-sized array of entries. */
+ unsigned long entries[]; /* Variable-sized array of entries. */
};
static void *stack_slabs[STACK_ALLOC_MAX_SLABS];
@@ -104,9 +104,8 @@ static bool init_stack_slab(void **prealloc)
static struct stack_record *depot_alloc_stack(unsigned long *entries, int size,
u32 hash, void **prealloc, gfp_t alloc_flags)
{
- int required_size = offsetof(struct stack_record, entries) +
- sizeof(unsigned long) * size;
struct stack_record *stack;
+ size_t required_size = struct_size(stack, entries, size);
required_size = ALIGN(required_size, 1 << STACK_ALLOC_ALIGN);
--
2.27.0
next prev parent reply other threads:[~2020-10-01 15:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 15:24 [PATCH 0/3][next] lib/stackdepot.c: Replace one-element array with flexible-array member Gustavo A. R. Silva
2020-10-01 15:25 ` Gustavo A. R. Silva [this message]
2020-10-01 15:25 ` [PATCH 2/3][next] lib/stackdepot.c: Use flex_array_size() helper in memcpy() Gustavo A. R. Silva
2020-10-01 15:26 ` [PATCH 3/3][next] lib/stackdepot.c: Use array_size() helper in jhash2() Gustavo A. R. Silva
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