diff options
| author | Kees Cook <keescook@chromium.org> | 2023-10-18 16:07:32 -0700 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2023-10-18 20:30:47 -0400 |
| commit | a180af9dd349d9819b13af43f877bea4f94c1c79 (patch) | |
| tree | 13917faa7e761706da5afe4b5af6bdcfb84c4fc4 | |
| parent | 1be06a61f1215f4026c93cb3bc1683ab2cab2b5a (diff) | |
bcachefs: Refactor memcpy into direct assignment
The memcpy() in bch2_bkey_append_ptr() is operating on an embedded fake
flexible array which looks to the compiler like it has 0 size. This
causes W=1 builds to emit warnings due to -Wstringop-overflow:
In file included from include/linux/string.h:254,
from include/linux/bitmap.h:11,
from include/linux/cpumask.h:12,
from include/linux/smp.h:13,
from include/linux/lockdep.h:14,
from include/linux/radix-tree.h:14,
from include/linux/backing-dev-defs.h:6,
from fs/bcachefs/bcachefs.h:182:
fs/bcachefs/extents.c: In function 'bch2_bkey_append_ptr':
include/linux/fortify-string.h:57:33: warning: writing 8 bytes into a region of size 0 [-Wstringop-overflow=]
57 | #define __underlying_memcpy __builtin_memcpy
| ^
include/linux/fortify-string.h:648:9: note: in expansion of macro '__underlying_memcpy'
648 | __underlying_##op(p, q, __fortify_size); \
| ^~~~~~~~~~~~~
include/linux/fortify-string.h:693:26: note: in expansion of macro '__fortify_memcpy_chk'
693 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \
| ^~~~~~~~~~~~~~~~~~~~
fs/bcachefs/extents.c:235:17: note: in expansion of macro 'memcpy'
235 | memcpy((void *) &k->v + bkey_val_bytes(&k->k),
| ^~~~~~
fs/bcachefs/bcachefs_format.h:287:33: note: destination object 'v' of size 0
287 | struct bch_val v;
| ^
Avoid making any structure changes and just replace the u64 copy into a
direct assignment, side-stepping the entire problem.
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Brian Foster <bfoster@redhat.com>
Cc: linux-bcachefs@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202309192314.VBsjiIm5-lkp@intel.com/
Link: https://lore.kernel.org/r/20231010235609.work.594-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
| -rw-r--r-- | fs/bcachefs/extents.h | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/fs/bcachefs/extents.h b/fs/bcachefs/extents.h index 978ae5e7e8b1..879e7d218b6a 100644 --- a/fs/bcachefs/extents.h +++ b/fs/bcachefs/extents.h @@ -633,6 +633,8 @@ void bch2_bkey_extent_entry_drop(struct bkey_i *, union bch_extent_entry *); static inline void bch2_bkey_append_ptr(struct bkey_i *k, struct bch_extent_ptr ptr) { + struct bch_extent_ptr *dest; + EBUG_ON(bch2_bkey_has_device(bkey_i_to_s(k), ptr.dev)); switch (k->k.type) { @@ -642,12 +644,8 @@ static inline void bch2_bkey_append_ptr(struct bkey_i *k, struct bch_extent_ptr EBUG_ON(bkey_val_u64s(&k->k) >= BKEY_EXTENT_VAL_U64s_MAX); ptr.type = 1 << BCH_EXTENT_ENTRY_ptr; - - unsafe_memcpy((void *) &k->v + bkey_val_bytes(&k->k), - &ptr, - sizeof(ptr), - "Our memcpy target is relative to a zero size array ," - "compiler bounds checking doesn't work here"); + dest = (struct bch_extent_ptr *)((void *) &k->v + bkey_val_bytes(&k->k)); + *dest = ptr; k->k.u64s++; break; default: |