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selftests/bpf: Add tests for rejection of ALU ops with negative offsets

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Define a simple program using MOD, DIV, ADD instructions,
make sure that the program is rejected if invalid offset
field is used for instruction.

These are test cases for
commit 55c0ced59f ("bpf: Reject negative offsets for ALU ops")
Link: https://lore.kernel.org/all/tencent_70D024BAE70A0A309A4781694C7B764B0608@qq.com/
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Eduard Zingerman 2025-10-02 12:11:40 -07:00 committed by Alexei Starovoitov
parent f09f57c746
commit 2ce61c63e7
1 changed files with 29 additions and 0 deletions
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29
tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c
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@ -3,6 +3,7 @@
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "../../../include/linux/filter.h"
#include "bpf_misc.h"
#define MAX_ENTRIES 11
@ -183,4 +184,32 @@ __naked void flow_keys_illegal_variable_offset_alu(void)
: __clobber_all);
}
#define DEFINE_BAD_OFFSET_TEST(name, op, off, imm) \
SEC("socket") \
__failure __msg("BPF_ALU uses reserved fields") \
__naked void name(void) \
{ \
asm volatile( \
"r0 = 1;" \
".8byte %[insn];" \
"r0 = 0;" \
"exit;" \
: \
: __imm_insn(insn, BPF_RAW_INSN((op), 0, 0, (off), (imm))) \
: __clobber_all); \
}
/*
* Offset fields of 0 and 1 are legal for BPF_{DIV,MOD} instructions.
* Offset fields of 0 are legal for the rest of ALU instructions.
* Test that error is reported for illegal offsets, assuming that tests
* for legal offsets exist.
*/
DEFINE_BAD_OFFSET_TEST(bad_offset_divx, BPF_ALU64 | BPF_DIV | BPF_X, -1, 0)
DEFINE_BAD_OFFSET_TEST(bad_offset_modk, BPF_ALU64 | BPF_MOD | BPF_K, -1, 1)
DEFINE_BAD_OFFSET_TEST(bad_offset_addx, BPF_ALU64 | BPF_ADD | BPF_X, -1, 0)
DEFINE_BAD_OFFSET_TEST(bad_offset_divx2, BPF_ALU64 | BPF_DIV | BPF_X, 2, 0)
DEFINE_BAD_OFFSET_TEST(bad_offset_modk2, BPF_ALU64 | BPF_MOD | BPF_K, 2, 1)
DEFINE_BAD_OFFSET_TEST(bad_offset_addx2, BPF_ALU64 | BPF_ADD | BPF_X, 1, 0)
char _license[] SEC("license") = "GPL";