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authorFlorent Revest <[email protected]>2021-04-27 13:29:58 +0200
committerAlexei Starovoitov <[email protected]>2021-04-27 08:04:34 -0700
commit38d26d89b31d0766d431471572cc9b007ca19c98 (patch)
tree2a4348b2fd79659c65fdade471284cd6108b58ff
parent927315041828fcbead6d2ace38c6dee5af95e40f (diff)
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 <[email protected]> Signed-off-by: Florent Revest <[email protected]> Signed-off-by: Alexei Starovoitov <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
-rw-r--r--kernel/trace/bpf_trace.c2
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);