diff options
| author | Florent Revest <revest@chromium.org> | 2021-04-27 13:29:58 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-04-27 08:04:34 -0700 |
| commit | 38d26d89b31d0766d431471572cc9b007ca19c98 (patch) | |
| tree | 2a4348b2fd79659c65fdade471284cd6108b58ff /kernel/trace | |
| parent | 927315041828fcbead6d2ace38c6dee5af95e40f (diff) | |
| download | lwn-38d26d89b31d0766d431471572cc9b007ca19c98.tar.gz lwn-38d26d89b31d0766d431471572cc9b007ca19c98.zip | |
bpf: Lock bpf_trace_printk's tmp buf before it is written to
bpf_trace_printk uses a shared static buffer to hold strings before they
are printed. A recent refactoring moved the locking of that buffer after
it gets filled by mistake.
Fixes: d9c9e4db186a ("bpf: Factorize bpf_trace_printk and bpf_seq_printf")
Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210427112958.773132-1-revest@chromium.org
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/bpf_trace.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 2a8bcdc927c7..0e67d12a8f40 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -391,13 +391,13 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, if (ret < 0) return ret; + raw_spin_lock_irqsave(&trace_printk_lock, flags); ret = snprintf(buf, sizeof(buf), fmt, BPF_CAST_FMT_ARG(0, args, mod), BPF_CAST_FMT_ARG(1, args, mod), BPF_CAST_FMT_ARG(2, args, mod)); /* snprintf() will not append null for zero-length strings */ if (ret == 0) buf[0] = '\0'; - raw_spin_lock_irqsave(&trace_printk_lock, flags); trace_bpf_trace_printk(buf); raw_spin_unlock_irqrestore(&trace_printk_lock, flags); |