On 18/04/2023 14:47, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@xxxxxxxx> The array_size() helper is used here to prevent accidental overflow in mlx4_init_user_cqes(), but as this returns SIZE_MAX in case an overflow would happen, the logic in copy_to_user() now detects that as overflowing the source: In file included from arch/x86/include/asm/preempt.h:9, from include/linux/preempt.h:78, from include/linux/percpu.h:6, from include/linux/context_tracking_state.h:5, from include/linux/hardirq.h:5, from drivers/net/ethernet/mellanox/mlx4/cq.c:37: In function 'check_copy_size', inlined from 'copy_to_user' at include/linux/uaccess.h:190:6, inlined from 'mlx4_init_user_cqes' at drivers/net/ethernet/mellanox/mlx4/cq.c:317:9, inlined from 'mlx4_cq_alloc' at drivers/net/ethernet/mellanox/mlx4/cq.c:394:10: include/linux/thread_info.h:244:4: error: call to '__bad_copy_from' declared with attribute error: copy source size is too small 244 | __bad_copy_from(); | ^~~~~~~~~~~~~~~~~ Move the size logic out, and instead use the same size value for the comparison and the copy. Fixes: f69bf5dee7ef ("net/mlx4: Use array_size() helper in copy_to_user()") Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> --- drivers/net/ethernet/mellanox/mlx4/cq.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/cq.c b/drivers/net/ethernet/mellanox/mlx4/cq.c index 4d4f9cf9facb..020cb8e2883f 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_size = array_size(entries, cqe_size); void *init_ents; int err = 0; int i; @@ -304,7 +305,7 @@ static int mlx4_init_user_cqes(void *buf, int entries, int cqe_size) */ memset(init_ents, 0xcc, PAGE_SIZE);- if (entries_per_copy < entries) {+ if (copy_size > PAGE_SIZE) { for (i = 0; i < entries / entries_per_copy; i++) { err = copy_to_user((void __user *)buf, init_ents, PAGE_SIZE) ? -EFAULT : 0; @@ -315,7 +316,7 @@ static int mlx4_init_user_cqes(void *buf, int entries, int cqe_size) } } else { err = copy_to_user((void __user *)buf, init_ents, - array_size(entries, cqe_size)) ? + copy_size) ? -EFAULT : 0; }
Reviewed-by: Tariq Toukan <tariqt@xxxxxxxxxx> Thanks for your patch.
