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SubjectRe: [Potential Spoof] [PATCH v2 bpf-next 3/4] bpf: allow %pB in bpf_seq_printf() and bpf_trace_printk()
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On 6/25/20 5:13 PM, Song Liu wrote:
> This makes it easy to dump stack trace in text.
>
> Signed-off-by: Song Liu <songliubraving@fb.com>

Ack with a small nit below.
Acked-by: Yonghong Song <yhs@fb.com>

> ---
> kernel/trace/bpf_trace.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 65fa62723e2f8..1cb90b0868817 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -376,7 +376,7 @@ static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype,
>
> /*
> * Only limited trace_printk() conversion specifiers allowed:
> - * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pks %pus %s
> + * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pB %pks %pus %s
> */
> BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
> u64, arg2, u64, arg3)
> @@ -420,6 +420,11 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
> goto fmt_str;
> }
>
> + if (fmt[i + 1] == 'B') {
> + i++;
> + goto fmt_next;
> + }
> +
> /* disallow any further format extensions */
> if (fmt[i + 1] != 0 &&
> !isspace(fmt[i + 1]) &&
> @@ -479,7 +484,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
> #define __BPF_TP_EMIT() __BPF_ARG3_TP()
> #define __BPF_TP(...) \
> __trace_printk(0 /* Fake ip */, \
> - fmt, ##__VA_ARGS__)
> + fmt, ##__VA_ARGS__)\

Accidental change?

>
> #define __BPF_ARG1_TP(...) \
> ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \
> @@ -636,7 +641,8 @@ BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size,
> if (fmt[i] == 'p') {
> if (fmt[i + 1] == 0 ||
> fmt[i + 1] == 'K' ||
> - fmt[i + 1] == 'x') {
> + fmt[i + 1] == 'x' ||
> + fmt[i + 1] == 'B') {
> /* just kernel pointers */
> params[fmt_cnt] = args[fmt_cnt];
> fmt_cnt++;
>

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