1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/bpf.h>
4 #include <bpf/bpf_helpers.h>
5 #include "bpf_misc.h"
6 
7 /* Read an uninitialized value from stack at a fixed offset */
8 SEC("socket")
9 __naked int read_uninit_stack_fixed_off(void *ctx)
10 {
11 	asm volatile ("					\
12 		r0 = 0;					\
13 		/* force stack depth to be 128 */	\
14 		*(u64*)(r10 - 128) = r1;		\
15 		r1 = *(u8 *)(r10 - 8 );			\
16 		r0 += r1;				\
17 		r1 = *(u8 *)(r10 - 11);			\
18 		r1 = *(u8 *)(r10 - 13);			\
19 		r1 = *(u8 *)(r10 - 15);			\
20 		r1 = *(u16*)(r10 - 16);			\
21 		r1 = *(u32*)(r10 - 32);			\
22 		r1 = *(u64*)(r10 - 64);			\
23 		/* read from a spill of a wrong size, it is a separate	\
24 		 * branch in check_stack_read_fixed_off()		\
25 		 */					\
26 		*(u32*)(r10 - 72) = r1;			\
27 		r1 = *(u64*)(r10 - 72);			\
28 		r0 = 0;					\
29 		exit;					\
30 "
31 		      ::: __clobber_all);
32 }
33 
34 /* Read an uninitialized value from stack at a variable offset */
35 SEC("socket")
36 __naked int read_uninit_stack_var_off(void *ctx)
37 {
38 	asm volatile ("					\
39 		call %[bpf_get_prandom_u32];		\
40 		/* force stack depth to be 64 */	\
41 		*(u64*)(r10 - 64) = r0;			\
42 		r0 = -r0;				\
43 		/* give r0 a range [-31, -1] */		\
44 		if r0 s<= -32 goto exit_%=;		\
45 		if r0 s>= 0 goto exit_%=;		\
46 		/* access stack using r0 */		\
47 		r1 = r10;				\
48 		r1 += r0;				\
49 		r2 = *(u8*)(r1 + 0);			\
50 exit_%=:	r0 = 0;					\
51 		exit;					\
52 "
53 		      :
54 		      : __imm(bpf_get_prandom_u32)
55 		      : __clobber_all);
56 }
57 
58 static __noinline void dummy(void) {}
59 
60 /* Pass a pointer to uninitialized stack memory to a helper.
61  * Passed memory block should be marked as STACK_MISC after helper call.
62  */
63 SEC("socket")
64 __log_level(7) __msg("fp-104=mmmmmmmm")
65 __naked int helper_uninit_to_misc(void *ctx)
66 {
67 	asm volatile ("					\
68 		/* force stack depth to be 128 */	\
69 		*(u64*)(r10 - 128) = r1;		\
70 		r1 = r10;				\
71 		r1 += -128;				\
72 		r2 = 32;				\
73 		call %[bpf_trace_printk];		\
74 		/* Call to dummy() forces print_verifier_state(..., true),	\
75 		 * thus showing the stack state, matched by __msg().		\
76 		 */					\
77 		call %[dummy];				\
78 		r0 = 0;					\
79 		exit;					\
80 "
81 		      :
82 		      : __imm(bpf_trace_printk),
83 			__imm(dummy)
84 		      : __clobber_all);
85 }
86 
87 char _license[] SEC("license") = "GPL";
88