Commit 079e5c56 authored by Mykyta Yatsenko's avatar Mykyta Yatsenko Committed by Andrii Nakryiko
Browse files

bpf: Fix error return value in bpf_copy_from_user_dynptr 



On error, copy_from_user returns number of bytes not copied to
destination, but current implementation of copy_user_data_sleepable does
not handle that correctly and returns it as error value, which may
confuse user, expecting meaningful negative error value.

Fixes: a498ee75 ("bpf: Implement dynptr copy kfuncs")
Reported-by: default avatarDan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: default avatarMykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250523181705.261585-1-mykyta.yatsenko5@gmail.com
parent bfccacdf

kernel/trace/bpf_trace.c

+6 −2
Original line number Diff line number Diff line
@@ -3555,8 +3555,12 @@ static __always_inline int copy_user_data_sleepable(void *dst, const void *unsaf 
{

	int ret;



	if (!tsk) /* Read from the current task */

		return copy_from_user(dst, (const void __user *)unsafe_src, size);

	if (!tsk) { /* Read from the current task */

		ret = copy_from_user(dst, (const void __user *)unsafe_src, size);

		if (ret)

			return -EFAULT;

		return 0;

	}



	ret = access_process_vm(tsk, (unsigned long)unsafe_src, dst, size, 0);

	if (ret != size)