From f19a4050455aad847fb93f18dc1fe502eb60f989 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Thu, 15 Dec 2022 22:44:29 +0100 Subject: bpf: Do cleanup in bpf_bprintf_cleanup only when needed 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 Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20221215214430.1336195-3-jolsa@kernel.org --- include/linux/bpf.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index cc390ba32e70..656879385fbf 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -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 { -- cgit v1.2.3