@@ -2803,7 +2803,7 @@ struct bpf_bprintf_data {
int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
u32 num_args, struct bpf_bprintf_data *data);
-void bpf_bprintf_cleanup(void);
+void bpf_bprintf_cleanup(struct bpf_bprintf_data *data);
/* the implementation of the opaque uapi struct bpf_dynptr */
struct bpf_dynptr_kern {
@@ -784,12 +784,14 @@ static int try_get_fmt_tmp_buf(char **tmp_buf)
return 0;
}
-void bpf_bprintf_cleanup(void)
+void bpf_bprintf_cleanup(struct bpf_bprintf_data *data)
{
- if (this_cpu_read(bpf_bprintf_nest_level)) {
- this_cpu_dec(bpf_bprintf_nest_level);
- preempt_enable();
- }
+ if (!data->bin_args)
+ return;
+ if (WARN_ON_ONCE(this_cpu_read(bpf_bprintf_nest_level) == 0))
+ return;
+ this_cpu_dec(bpf_bprintf_nest_level);
+ preempt_enable();
}
/*
@@ -1021,7 +1023,7 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
err = 0;
out:
if (err)
- bpf_bprintf_cleanup();
+ bpf_bprintf_cleanup(data);
return err;
}
@@ -1047,7 +1049,7 @@ BPF_CALL_5(bpf_snprintf, char *, str, u32, str_size, char *, fmt,
err = bstr_printf(str, str_size, fmt, data.bin_args);
- bpf_bprintf_cleanup();
+ bpf_bprintf_cleanup(&data);
return err + 1;
}
@@ -396,7 +396,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
trace_bpf_trace_printk(buf);
raw_spin_unlock_irqrestore(&trace_printk_lock, flags);
- bpf_bprintf_cleanup();
+ bpf_bprintf_cleanup(&data);
return ret;
}
@@ -454,7 +454,7 @@ BPF_CALL_4(bpf_trace_vprintk, char *, fmt, u32, fmt_size, const void *, args,
trace_bpf_trace_printk(buf);
raw_spin_unlock_irqrestore(&trace_printk_lock, flags);
- bpf_bprintf_cleanup();
+ bpf_bprintf_cleanup(&data);
return ret;
}
@@ -494,7 +494,7 @@ BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size,
seq_bprintf(m, fmt, data.bin_args);
- bpf_bprintf_cleanup();
+ bpf_bprintf_cleanup(&data);
return seq_has_overflowed(m) ? -EOVERFLOW : 0;
}
Currently we always cleanup/decrement bpf_bprintf_nest_level variable in bpf_bprintf_cleanup if it's > 0. There's possible scenario where this could cause a problem, when bpf_bprintf_prepare does not get bin_args buffer (because num_args is 0) and following bpf_bprintf_cleanup call decrements bpf_bprintf_nest_level variable, like: in task context: bpf_bprintf_prepare(num_args != 0) increments 'bpf_bprintf_nest_level = 1' -> first irq : bpf_bprintf_prepare(num_args == 0) bpf_bprintf_cleanup decrements 'bpf_bprintf_nest_level = 0' -> second irq: bpf_bprintf_prepare(num_args != 0) bpf_bprintf_nest_level = 1 gets same buffer as task context above Adding check to bpf_bprintf_cleanup and doing the real cleanup only if we got bin_args data in the first place. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- include/linux/bpf.h | 2 +- kernel/bpf/helpers.c | 16 +++++++++------- kernel/trace/bpf_trace.c | 6 +++--- 3 files changed, 13 insertions(+), 11 deletions(-)