diff options
| author | Matteo Croce <[email protected]> | 2024-10-10 04:56:52 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <[email protected]> | 2024-10-10 08:52:36 -0700 |
| commit | 5bd48a3a14df4b3ee1be0757efcc0f40d4f57b35 (patch) | |
| tree | 65e2ea6fdecffdfec494ec9b8ee4cd985d136d42 | |
| parent | 4073213488be542f563eb4b2457ab4cbcfc2b738 (diff) | |
bpf: fix argument type in bpf_loop documentation
The `index` argument to bpf_loop() is threaded as an u64.
This lead in a subtle verifier denial where clang cloned the argument
in another register[1].
[1] https://github.com/systemd/systemd/pull/34650#issuecomment-2401092895
Signed-off-by: Matteo Croce <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
| -rw-r--r-- | include/uapi/linux/bpf.h | 2 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 2 | ||||
| -rw-r--r-- | tools/include/uapi/linux/bpf.h | 2 |
3 files changed, 3 insertions, 3 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 8ab4d8184b9d..874af0186fe8 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5371,7 +5371,7 @@ union bpf_attr { * Currently, the **flags** must be 0. Currently, nr_loops is * limited to 1 << 23 (~8 million) loops. * - * long (\*callback_fn)(u32 index, void \*ctx); + * long (\*callback_fn)(u64 index, void \*ctx); * * where **index** is the current index in the loop. The index * is zero-indexed. diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7d9b38ffd220..cfc62e0776bf 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9917,7 +9917,7 @@ static int set_loop_callback_state(struct bpf_verifier_env *env, { /* bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx, * u64 flags); - * callback_fn(u32 index, void *callback_ctx); + * callback_fn(u64 index, void *callback_ctx); */ callee->regs[BPF_REG_1].type = SCALAR_VALUE; callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3]; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 7610883c8191..5937c39069ba 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5371,7 +5371,7 @@ union bpf_attr { * Currently, the **flags** must be 0. Currently, nr_loops is * limited to 1 << 23 (~8 million) loops. * - * long (\*callback_fn)(u32 index, void \*ctx); + * long (\*callback_fn)(u64 index, void \*ctx); * * where **index** is the current index in the loop. The index * is zero-indexed. |