mlx4_init_user_cqes() fills a scratch buffer with the CQE initialization pattern and then copies from that buffer to userspace. In the single-copy path, the copy length is array_size(entries, cqe_size), but the scratch buffer is allocated with PAGE_SIZE. GCC 10 does not carry the branch invariant strongly enough through the object size checks and falsely triggers __bad_copy_from(). Size the scratch buffer to the actual copy length for the active path, keep array_size() for the single-copy case, and retain a WARN_ON_ONCE() guard for the PAGE_SIZE invariant before allocating the buffer. Fixes: f69bf5dee7ef ("net/mlx4: Use array_size() helper in copy_to_user()") Signed-off-by: Yao Sang --- Changes in v2: - Replace silent clamping with WARN_ON_ONCE guard for array_size() over PAGE_SIZE, return -EINVAL. drivers/net/ethernet/mellanox/mlx4/cq.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/cq.c b/drivers/net/ethernet/mellanox/mlx4/cq.c index e130e7259275..5c55971abbf0 100644 --- a/drivers/net/ethernet/mellanox/mlx4/cq.c +++ b/drivers/net/ethernet/mellanox/mlx4/cq.c @@ -290,6 +290,7 @@ static void mlx4_cq_free_icm(struct mlx4_dev *dev, int cqn) static int mlx4_init_user_cqes(void *buf, int entries, int cqe_size) { int entries_per_copy = PAGE_SIZE / cqe_size; + size_t copy_bytes; void *init_ents; int err = 0; int i; @@ -314,8 +315,14 @@ static int mlx4_init_user_cqes(void *buf, int entries, int cqe_size) buf += PAGE_SIZE; } } else { + copy_bytes = array_size(entries, cqe_size); + if (WARN_ON_ONCE(copy_bytes > PAGE_SIZE)) { + err = -EINVAL; + goto out; + } + err = copy_to_user((void __user *)buf, init_ents, - array_size(entries, cqe_size)) ? + copy_bytes) ? -EFAULT : 0; } -- 2.25.1