struct bkey has internal padding in a union, but it isn't always named the same (e.g. key ## _pad, key_p, etc). This makes it extremely hard for the compiler to reason about the available size of copies done against such keys. Use unsafe_memcpy() for now, to silence the many run-time false positive warnings: memcpy: detected field-spanning write (size 264) of single field "&i->j" at drivers/md/bcache/journal.c:152 (size 240) memcpy: detected field-spanning write (size 24) of single field "&b->key" at drivers/md/bcache/btree.c:939 (size 16) emcpy: detected field-spanning write (size 24) of single field "&temp.key" at drivers/md/bcache/extents.c:428 (size 16) Reported-by: Thorsten Leemhuis <linux@xxxxxxxxxxxxx> Link: https://lore.kernel.org/all/19200730-a3ba-6f4f-bb81-71339bdbbf73@xxxxxxxxxxxxx/ Cc: Coly Li <colyli@xxxxxxx> Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx> Cc: linux-bcache@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- drivers/md/bcache/bcache_ondisk.h | 3 ++- drivers/md/bcache/journal.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/md/bcache/bcache_ondisk.h b/drivers/md/bcache/bcache_ondisk.h index d086a0ce4bc2..6620a7f8fffc 100644 --- a/drivers/md/bcache/bcache_ondisk.h +++ b/drivers/md/bcache/bcache_ondisk.h @@ -106,7 +106,8 @@ static inline unsigned long bkey_bytes(const struct bkey *k) return bkey_u64s(k) * sizeof(__u64); } -#define bkey_copy(_dest, _src) memcpy(_dest, _src, bkey_bytes(_src)) +#define bkey_copy(_dest, _src) unsafe_memcpy(_dest, _src, bkey_bytes(_src), \ + /* bkey is always padded */) static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src) { diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c index e5da469a4235..c182c21de2e8 100644 --- a/drivers/md/bcache/journal.c +++ b/drivers/md/bcache/journal.c @@ -149,7 +149,8 @@ reread: left = ca->sb.bucket_size - offset; bytes, GFP_KERNEL); if (!i) return -ENOMEM; - memcpy(&i->j, j, bytes); + unsafe_memcpy(&i->j, j, bytes, + /* "bytes" was calculated by set_bytes() above */); /* Add to the location after 'where' points to */ list_add(&i->list, where); ret = 1; -- 2.34.1
