| Message ID | ZSQ/jcmTAf/PKHg/@work (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Johannes Berg |
| Headers | show |
| Series | [next] wifi: mac80211: Add __counted_by for struct ieee802_11_elems and use struct_size() | expand |
On Mon, Oct 09, 2023 at 11:59:41AM -0600, Gustavo A. R. Silva wrote: > 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 via CONFIG_UBSAN_BOUNDS (for > array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family > functions). > > While there, use struct_size() helper, instead of the open-coded > version, to calculate the size for the allocation of the whole > flexible structure including, of course, the flexible-array member. > > This code was found with the help of Coccinelle, and audited and > fixed manually. > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Looks correct: "scratch" isn't accessed before setting "scratch_len". Reviewed-by: Kees Cook <keescook@chromium.org> -Kees
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index e92eaf835ee0..0d3d386445c5 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -1746,7 +1746,7 @@ struct ieee802_11_elems { */ size_t scratch_len; u8 *scratch_pos; - u8 scratch[]; + u8 scratch[] __counted_by(scratch_len); }; static inline struct ieee80211_local *hw_to_local( diff --git a/net/mac80211/util.c b/net/mac80211/util.c index 98a3bffc6991..a91b0e7795a4 100644 --- a/net/mac80211/util.c +++ b/net/mac80211/util.c @@ -1612,7 +1612,7 @@ ieee802_11_parse_elems_full(struct ieee80211_elems_parse_params *params) int nontransmitted_profile_len = 0; size_t scratch_len = 3 * params->len; - elems = kzalloc(sizeof(*elems) + scratch_len, GFP_ATOMIC); + elems = kzalloc(struct_size(elems, scratch, scratch_len), GFP_ATOMIC); if (!elems) return NULL; elems->ie_start = params->start;
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 via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions). While there, use struct_size() helper, instead of the open-coded version, to calculate the size for the allocation of the whole flexible structure including, of course, the flexible-array member. This code was found with the help of Coccinelle, and audited and fixed manually. Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- net/mac80211/ieee80211_i.h | 2 +- net/mac80211/util.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)