// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <limits.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
SEC("socket")
__description("scalars: find linked scalars")
__failure
__msg("math between fp pointer and 2147483647 is not allowed")
__naked void scalars(void)
{
asm volatile (" \
r0 = 0; \
r1 = 0x80000001 ll; \
r1 /= 1; \
r2 = r1; \
r4 = r1; \
w2 += 0x7FFFFFFF; \
w4 += 0; \
if r2 == 0 goto l0_%=; \
exit; \
l0_%=: \
r4 >>= 63; \
r3 = 1; \
r3 -= r4; \
r3 *= 0x7FFFFFFF; \
r3 += r10; \
*(u8*)(r3 - 1) = r0; \
exit; \
" ::: __clobber_all);
}
/*
* Test that sync_linked_regs() preserves register IDs.
*
* The sync_linked_regs() function copies bounds from known_reg to linked
* registers. When doing so, it must preserve each register's original id
* to allow subsequent syncs from the same source to work correctly.
*
*/
SEC("socket")
__success
__naked void sync_linked_regs_preserves_id(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 0xff; /* r0 in [0, 255] */ \
r1 = r0; /* r0, r1 linked with id 1 */ \
r1 += 4; /* r1 has id=1 and off=4 in [4, 259] */ \
if r1 < 10 goto l0_%=; \
/* r1 in [10, 259], r0 synced to [6, 255] */ \
r2 = r0; /* r2 has id=1 and in [6, 255] */ \
if r1 < 14 goto l0_%=; \
/* r1 in [14, 259], r0 synced to [10, 255] */ \
if r0 >= 10 goto l0_%=; \
/* Never executed */ \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
SEC("socket")
__success
__naked void scalars_neg(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 0xff; \
r1 = r0; \
r1 += -4; \
if r1 s< 0 goto l0_%=; \
if r0 != 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/* Same test but using BPF_SUB instead of BPF_ADD with negative immediate */
SEC("socket")
__success
__naked void scalars_neg_sub(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 0xff; \
r1 = r0; \
r1 -= 4; \
if r1 s< 0 goto l0_%=; \
if r0 != 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/* alu32 with negative offset */
SEC("socket")
__success
__naked void scalars_neg_alu32_add(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
w0 &= 0xff; \
w1 = w0; \
w1 += -4; \
if w1 s< 0 goto l0_%=; \
if w0 != 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/* alu32 with negative offset using SUB */
SEC("socket")
__success
__naked void scalars_neg_alu32_sub(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
w0 &= 0xff; \
w1 = w0; \
w1 -= 4; \
if w1 s< 0 goto l0_%=; \
if w0 != 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/* Positive offset: r1 = r0 + 4, then if r1 >= 6, r0 >= 2, so r0 != 0 */
SEC("socket")
__success
__naked void scalars_pos(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 0xff; \
r1 = r0; \
r1 += 4; \
if r1 < 6 goto l0_%=; \
if r0 != 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/* SUB with negative immediate: r1 -= -4 is equivalent to r1 += 4 */
SEC("socket")
__success
__naked void scalars_sub_neg_imm(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 0xff; \
r1 = r0; \
r1 -= -4; \
if r1 < 6 goto l0_%=; \
if r0 != 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/* Double ADD clears the ID (can't accumulate offsets) */
SEC("socket")
__failure
__msg("div by zero")
__naked void scalars_double_add(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 0xff; \
r1 = r0; \
r1 += 2; \
r1 += 2; \
if r1 < 6 goto l0_%=; \
if r0 != 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/*
* Test that sync_linked_regs() correctly handles large offset differences.
* r1.off = S32_MIN, r2.off = 1, delta = S32_MIN - 1 requires 64-bit math.
*/
SEC("socket")
__success
__naked void scalars_sync_delta_overflow(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 0xff; \
r1 = r0; \
r2 = r0; \
r1 += %[s32_min]; \
r2 += 1; \
if r2 s< 100 goto l0_%=; \
if r1 s< 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32),
[s32_min]"i"(INT_MIN)
: __clobber_all);
}
/*
* Another large delta case: r1.off = S32_MAX, r2.off = -1.
* delta = S32_MAX - (-1) = S32_MAX + 1 requires 64-bit math.
*/
SEC("socket")
__success
__naked void scalars_sync_delta_overflow_large_range(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r0 &= 0xff; \
r1 = r0; \
r2 = r0; \
r1 += %[s32_max]; \
r2 += -1; \
if r2 s< 0 goto l0_%=; \
if r1 s>= 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32),
[s32_max]"i"(INT_MAX)
: __clobber_all);
}
/*
* Test linked scalar tracking with alu32 and large positive offset (0x7FFFFFFF).
* After w1 += 0x7FFFFFFF, w1 wraps to negative for any r0 >= 1.
* If w1 is signed-negative, then r0 >= 1, so r0 != 0.
*/
SEC("socket")
__success
__naked void scalars_alu32_big_offset(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
w0 &= 0xff; \
w1 = w0; \
w1 += 0x7FFFFFFF; \
if w1 s>= 0 goto l0_%=; \
if w0 != 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
SEC("socket")
__failure
__msg("div by zero")
__naked void scalars_alu32_basic(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r1 = r0; \
w1 += 1; \
if r1 > 10 goto 1f; \
r0 >>= 32; \
if r0 == 0 goto 1f; \
r0 /= 0; \
1: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/*
* Test alu32 linked register tracking with wrapping.
* R0 is bounded to [0xffffff00, 0xffffffff] (high 32-bit values)
* w1 += 0x100 causes R1 to wrap to [0, 0xff]
*
* After sync_linked_regs, if bounds are computed correctly:
* R0 should be [0x00000000_ffffff00, 0x00000000_ffffff80]
* R0 >> 32 == 0, so div by zero is unreachable
*
* If bounds are computed incorrectly (64-bit underflow):
* R0 becomes [0xffffffff_ffffff00, 0xffffffff_ffffff80]
* R0 >> 32 == 0xffffffff != 0, so div by zero is reachable
*/
SEC("socket")
__success
__naked void scalars_alu32_wrap(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
w0 |= 0xffffff00; \
r1 = r0; \
w1 += 0x100; \
if r1 > 0x80 goto l0_%=; \
r2 = r0; \
r2 >>= 32; \
if r2 == 0 goto l0_%=; \
r0 /= 0; \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/*
* Test that sync_linked_regs() checks reg->id (the linked target register)
* for BPF_ADD_CONST32 rather than known_reg->id (the branch register).
*/
SEC("socket")
__success
__naked void scalars_alu32_zext_linked_reg(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
w6 = w0; /* r6 in [0, 0xFFFFFFFF] */ \
r7 = r6; /* linked: same id as r6 */ \
w7 += 1; /* alu32: r7.id |= BPF_ADD_CONST32 */ \
r8 = 0xFFFFffff ll; \
if r6 < r8 goto l0_%=; \
/* r6 in [0xFFFFFFFF, 0xFFFFFFFF] */ \
/* sync_linked_regs: known_reg=r6, reg=r7 */ \
/* CPU: w7 = (u32)(0xFFFFFFFF + 1) = 0, zext -> r7 = 0 */ \
/* With fix: r7 64-bit = [0, 0] (zext applied) */ \
/* Without fix: r7 64-bit = [0x100000000] (no zext) */ \
r7 >>= 32; \
if r7 == 0 goto l0_%=; \
r0 /= 0; /* unreachable with fix */ \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/*
* Test that sync_linked_regs() skips propagation when one register used
* alu32 (BPF_ADD_CONST32) and the other used alu64 (BPF_ADD_CONST64).
* The delta relationship doesn't hold across different ALU widths.
*/
SEC("socket")
__failure __msg("div by zero")
__naked void scalars_alu32_alu64_cross_type(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
w6 = w0; /* r6 in [0, 0xFFFFFFFF] */ \
r7 = r6; /* linked: same id as r6 */ \
w7 += 1; /* alu32: BPF_ADD_CONST32, delta = 1 */ \
r8 = r6; /* linked: same id as r6 */ \
r8 += 2; /* alu64: BPF_ADD_CONST64, delta = 2 */ \
r9 = 0xFFFFffff ll; \
if r7 < r9 goto l0_%=; \
/* r7 = 0xFFFFFFFF */ \
/* sync: known_reg=r7 (ADD_CONST32), reg=r8 (ADD_CONST64) */ \
/* Without fix: r8 = zext(0xFFFFFFFF + 1) = 0 */ \
/* With fix: r8 stays [2, 0x100000001] (r8 >= 2) */ \
if r8 > 0 goto l1_%=; \
goto l0_%=; \
l1_%=: \
r0 /= 0; /* div by zero */ \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/*
* Test that regsafe() prevents pruning when two paths reach the same program
* point with linked registers carrying different ADD_CONST flags (one
* BPF_ADD_CONST32 from alu32, another BPF_ADD_CONST64 from alu64).
*/
SEC("socket")
__failure __msg("div by zero")
__flag(BPF_F_TEST_STATE_FREQ)
__naked void scalars_alu32_alu64_regsafe_pruning(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
w6 = w0; /* r6 in [0, 0xFFFFFFFF] */ \
r7 = r6; /* linked: same id as r6 */ \
/* Get another random value for the path branch */ \
call %[bpf_get_prandom_u32]; \
if r0 > 0 goto l_pathb_%=; \
/* Path A: alu32 */ \
w7 += 1; /* BPF_ADD_CONST32, delta = 1 */\
goto l_merge_%=; \
l_pathb_%=: \
/* Path B: alu64 */ \
r7 += 1; /* BPF_ADD_CONST64, delta = 1 */\
l_merge_%=: \
/* Merge point: regsafe() compares path B against cached path A. */ \
/* Narrow r6 to trigger sync_linked_regs for r7 */ \
r9 = 0xFFFFffff ll; \
if r6 < r9 goto l0_%=; \
/* r6 = 0xFFFFFFFF */ \
/* sync: r7 = 0xFFFFFFFF + 1 = 0x100000000 */ \
/* Path A: zext -> r7 = 0 */ \
/* Path B: no zext -> r7 = 0x100000000 */ \
r7 >>= 32; \
if r7 == 0 goto l0_%=; \
r0 /= 0; /* div by zero on path B */ \
l0_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
SEC("socket")
__success
void alu32_negative_offset(void)
{
volatile char path[5];
volatile int offset = bpf_get_prandom_u32();
int off = offset;
if (off >= 5 && off < 10)
path[off - 5] = '.';
/* So compiler doesn't say: error: variable 'path' set but not used */
__sink(path[0]);
}
void dummy_calls(void)
{
bpf_iter_num_new(0, 0, 0);
bpf_iter_num_next(0);
bpf_iter_num_destroy(0);
}
SEC("socket")
__success
__flag(BPF_F_TEST_STATE_FREQ)
int spurious_precision_marks(void *ctx)
{
struct bpf_iter_num iter;
asm volatile(
"r1 = %[iter];"
"r2 = 0;"
"r3 = 10;"
"call %[bpf_iter_num_new];"
"1:"
"r1 = %[iter];"
"call %[bpf_iter_num_next];"
"if r0 == 0 goto 4f;"
"r7 = *(u32 *)(r0 + 0);"
"r8 = *(u32 *)(r0 + 0);"
/* This jump can't be predicted and does not change r7 or r8 state. */
"if r7 > r8 goto 2f;"
/* Branch explored first ties r2 and r7 as having the same id. */
"r2 = r7;"
"goto 3f;"
"2:"
/* Branch explored second does not tie r2 and r7 but has a function call. */
"call %[bpf_get_prandom_u32];"
"3:"
/*
* A checkpoint.
* When first branch is explored, this would inject linked registers
* r2 and r7 into the jump history.
* When second branch is explored, this would be a cache hit point,
* triggering propagate_precision().
*/
"if r7 <= 42 goto +0;"
/*
* Mark r7 as precise using an if condition that is always true.
* When reached via the second branch, this triggered a bug in the backtrack_insn()
* because r2 (tied to r7) was propagated as precise to a call.
*/
"if r7 <= 0xffffFFFF goto +0;"
"goto 1b;"
"4:"
"r1 = %[iter];"
"call %[bpf_iter_num_destroy];"
:
: __imm_ptr(iter),
__imm(bpf_iter_num_new),
__imm(bpf_iter_num_next),
__imm(bpf_iter_num_destroy),
__imm(bpf_get_prandom_u32)
: __clobber_common, "r7", "r8"
);
return 0;
}
/*
* Test that r += r (self-add, src_reg == dst_reg) clears the scalar ID
* so that sync_linked_regs() does not propagate an incorrect delta.
*/
SEC("socket")
__failure
__msg("div by zero")
__naked void scalars_self_add_clears_id(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r6 = r0; /* r6 unknown, id A */ \
r7 = r6; /* r7 linked to r6, id A */ \
call %[bpf_get_prandom_u32]; \
r8 = r0; /* r8 unknown, id B */ \
r9 = r8; /* r9 linked to r8, id B */ \
if r7 != 1 goto l_exit_%=; \
/* r7 == 1; sync propagates: r6 = 1 (known, id A) */ \
r6 += r6; /* r6 = 2; should clear id */ \
if r7 == r9 goto l_exit_%=; \
/* Bug: r6 synced to r7(1)+delta(2)=3; Fix: r6 = 2 */ \
if r6 == 3 goto l_exit_%=; \
r0 /= 0; \
l_exit_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/* Same as above but with alu32 such that w6 += w6 also clears id. */
SEC("socket")
__failure
__msg("div by zero")
__naked void scalars_self_add_alu32_clears_id(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
w6 = w0; \
w7 = w6; \
call %[bpf_get_prandom_u32]; \
w8 = w0; \
w9 = w8; \
if w7 != 1 goto l_exit_%=; \
w6 += w6; \
if w7 == w9 goto l_exit_%=; \
if w6 == 3 goto l_exit_%=; \
r0 /= 0; \
l_exit_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/*
* Test that stale delta from a cleared BPF_ADD_CONST does not leak
* through assign_scalar_id_before_mov() into a new id, causing
* sync_linked_regs() to compute an incorrect offset.
*/
SEC("socket")
__failure
__msg("div by zero")
__naked void scalars_stale_delta_from_cleared_id(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r6 = r0; /* r6 unknown, gets id A */ \
r6 += 5; /* id A|ADD_CONST, delta 5 */ \
r6 ^= 0; /* id cleared; delta stays 5 */ \
r8 = r6; /* new id B, stale delta 5 */ \
r8 += 3; /* id B|ADD_CONST, delta 3 */ \
r9 = r6; /* id B, stale delta 5 */ \
if r9 != 10 goto l_exit_%=; \
/* Bug: r8 = 10+(3-5) = 8; Fix: r8 = 10+(3-0) = 13 */ \
if r8 == 8 goto l_exit_%=; \
r0 /= 0; \
l_exit_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/* Same as above but with alu32. */
SEC("socket")
__failure
__msg("div by zero")
__naked void scalars_stale_delta_from_cleared_id_alu32(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
w6 = w0; \
w6 += 5; \
w6 ^= 0; \
w8 = w6; \
w8 += 3; \
w9 = w6; \
if w9 != 10 goto l_exit_%=; \
if w8 == 8 goto l_exit_%=; \
r0 /= 0; \
l_exit_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
/*
* Test that regsafe() verifies base_id consistency for BPF_ADD_CONST
* linked scalars during state pruning.
*
* The false branch (explored first) links R3 to R2 via ADD_CONST.
* The true branch (runtime path) links R3 to R4 (unrelated base_id).
* At the merge point, pruning must fail because the linkage topology
* differs.
*/
SEC("socket")
__description("linked scalars: add_const base_id must be consistent for pruning")
__failure __msg("invalid variable-offset")
__flag(BPF_F_TEST_STATE_FREQ)
__naked void add_const_base_id_pruning(void)
{
asm volatile (" \
r1 = 0; \
*(u64*)(r10 - 16) = r1; \
call %[bpf_get_prandom_u32]; \
r6 = r0; \
r6 &= 1; \
if r6 >= 1 goto l_true_%=; \
\
/* False branch (explored first, old state) */ \
call %[bpf_get_prandom_u32]; \
r2 = r0; \
r2 &= 0xff; /* R2 = scalar(id=A) [0,255] */ \
r3 = r2; /* R3 linked to R2 (id=A) */ \
r3 += 10; /* R3 id=A|ADD_CONST, delta=10 */\
r6 = 0; \
goto l_merge_%=; \
\
l_true_%=: \
/* True branch (runtime path, cur state) */ \
call %[bpf_get_prandom_u32]; \
r2 = r0; \
r2 &= 0xff; /* R2 = scalar [0,255], id=0 */ \
r4 = r0; \
r4 &= 0xff; /* R4 = scalar [0,255], id=0 */ \
r3 = r4; /* R3 linked to R4 (new id=C) */\
r3 += 10; /* R3 id=C|ADD_CONST, delta=10 */\
r6 = 0; \
\
l_merge_%=: \
/* At merge, old R3 linked to R2, cur R3 linked to R4. */\
/* Pruning must fail: base_ids A vs C inconsistent. */ \
if r2 >= 6 goto l_exit_%=; \
/* sync_linked_regs: R2<6 => R3<16 in old state. */ \
/* Without fix: R3 in [10,15] from incorrect pruning. */\
/* With fix: R3 in [10,265], not synced from R2. */ \
r3 -= 10; /* [0,5] vs [0,255] */ \
r9 = r10; \
r9 += -16; \
r9 += r3; /* fp-16+[0,5] vs fp-16+[0,255] */\
*(u8*)(r9 + 0) = r6; /* within 16B vs past fp */ \
l_exit_%=: \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
char _license[] SEC("license") = "GPL";
