Merge branch 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[deliverable/linux.git] / kernel / bpf / helpers.c

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 50da680c479f030588314ed664c8d57200c28990..ad7a0573f71bcb26fb3956d8e1c802f3e5e64b87 100644 (file)
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -163,17 +163,26 @@ static u64 bpf_get_current_comm(u64 r1, u64 size, u64 r3, u64 r4, u64 r5)
        struct task_struct *task = current;
        char *buf = (char *) (long) r1;
 
-       if (!task)
-               return -EINVAL;
+       if (unlikely(!task))
+               goto err_clear;
 
-       strlcpy(buf, task->comm, min_t(size_t, size, sizeof(task->comm)));
+       strncpy(buf, task->comm, size);
+
+       /* Verifier guarantees that size > 0. For task->comm exceeding
+        * size, guarantee that buf is %NUL-terminated. Unconditionally
+        * done here to save the size test.
+        */
+       buf[size - 1] = 0;
        return 0;
+err_clear:
+       memset(buf, 0, size);
+       return -EINVAL;
 }
 
 const struct bpf_func_proto bpf_get_current_comm_proto = {
        .func           = bpf_get_current_comm,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
-       .arg1_type      = ARG_PTR_TO_STACK,
+       .arg1_type      = ARG_PTR_TO_RAW_STACK,
        .arg2_type      = ARG_CONST_STACK_SIZE,
 };