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| author | Andrei Matei <andreimatei1@gmail.com> | 2023-12-22 00:22:25 +0100 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-01-03 19:37:56 +0100 |
| commit | 72187506de4f19fcc8ae63a2b2f36d75e5259d9d (patch) | |
| tree | d58e59ba6536fc754d8aed14bd7ef6a2a3fe2be0 /tools | |
| parent | bpf: Simplify checking size of helper accesses (diff) | |
| download | linux-72187506de4f19fcc8ae63a2b2f36d75e5259d9d.tar.xz linux-72187506de4f19fcc8ae63a2b2f36d75e5259d9d.zip | |
bpf: Add a possibly-zero-sized read test
This patch adds a test for the condition that the previous patch mucked
with - illegal zero-sized helper memory access. As opposed to existing
tests, this new one uses a size whose lower bound is zero, as opposed to
a known-zero one.
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231221232225.568730-3-andreimatei1@gmail.com
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/bpf/progs/verifier_helper_value_access.c | 39 |
1 files changed, 38 insertions, 1 deletions
diff --git a/tools/testing/selftests/bpf/progs/verifier_helper_value_access.c b/tools/testing/selftests/bpf/progs/verifier_helper_value_access.c index 3e8340c2408f..886498b5e6f3 100644 --- a/tools/testing/selftests/bpf/progs/verifier_helper_value_access.c +++ b/tools/testing/selftests/bpf/progs/verifier_helper_value_access.c @@ -89,9 +89,14 @@ l0_%=: exit; \ : __clobber_all); } +/* Call a function taking a pointer and a size which doesn't allow the size to + * be zero (i.e. bpf_trace_printk() declares the second argument to be + * ARG_CONST_SIZE, not ARG_CONST_SIZE_OR_ZERO). We attempt to pass zero for the + * size and expect to fail. + */ SEC("tracepoint") __description("helper access to map: empty range") -__failure __msg("R2 invalid zero-sized read") +__failure __msg("R2 invalid zero-sized read: u64=[0,0]") __naked void access_to_map_empty_range(void) { asm volatile (" \ @@ -113,6 +118,38 @@ l0_%=: exit; \ : __clobber_all); } +/* Like the test above, but this time the size register is not known to be zero; + * its lower-bound is zero though, which is still unacceptable. + */ +SEC("tracepoint") +__description("helper access to map: possibly-empty ange") +__failure __msg("R2 invalid zero-sized read: u64=[0,4]") +__naked void access_to_map_possibly_empty_range(void) +{ + asm volatile (" \ + r2 = r10; \ + r2 += -8; \ + r1 = 0; \ + *(u64*)(r2 + 0) = r1; \ + r1 = %[map_hash_48b] ll; \ + call %[bpf_map_lookup_elem]; \ + if r0 == 0 goto l0_%=; \ + r1 = r0; \ + /* Read an unknown value */ \ + r7 = *(u64*)(r0 + 0); \ + /* Make it small and positive, to avoid other errors */ \ + r7 &= 4; \ + r2 = 0; \ + r2 += r7; \ + call %[bpf_trace_printk]; \ +l0_%=: exit; \ +" : + : __imm(bpf_map_lookup_elem), + __imm(bpf_trace_printk), + __imm_addr(map_hash_48b) + : __clobber_all); +} + SEC("tracepoint") __description("helper access to map: out-of-bound range") __failure __msg("invalid access to map value, value_size=48 off=0 size=56") |