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Peter Anvin" , Ingo Molnar , Palmer Dabbelt , Paul Walmsley , Sven Schnelle , Thomas Gleixner , Vasily Gorbik , x86@kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, Conor Dooley , Jiri Olsa , Yonghong Song , Ze Gao , stable@vger.kernel.org Subject: [PATCH v2 3/4] fprobe: add recursion detection in fprobe_exit_handler Date: Tue, 16 May 2023 15:18:29 +0800 Message-Id: <20230516071830.8190-4-zegao@tencent.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230516071830.8190-1-zegao@tencent.com> References: <20230516071830.8190-1-zegao@tencent.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org fprobe_hander and fprobe_kprobe_handler has guarded ftrace recursion detection but fprobe_exit_handler has not, which possibly introduce recursive calls if the fprobe exit callback calls any traceable functions. Checking in fprobe_hander or fprobe_kprobe_handler is not enough and misses this case. So add recursion free guard the same way as fprobe_hander. Since ftrace recursion check does not employ ip(s), so here use entry_ip and entry_parent_ip the same as fprobe_handler. Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support") Signed-off-by: Ze Gao Cc: stable@vger.kernel.org Acked-by: Masami Hiramatsu (Google) --- kernel/trace/fprobe.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index 097c740799ba..a9580a88cc15 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -17,6 +17,7 @@ struct fprobe_rethook_node { struct rethook_node node; unsigned long entry_ip; + unsigned long entry_parent_ip; char data[]; }; @@ -39,6 +40,7 @@ static inline void __fprobe_handler(unsigned long ip, unsigned long } fpr = container_of(rh, struct fprobe_rethook_node, node); fpr->entry_ip = ip; + fpr->entry_parent_ip = parent_ip; if (fp->entry_data_size) entry_data = fpr->data; } @@ -114,14 +116,25 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data, { struct fprobe *fp = (struct fprobe *)data; struct fprobe_rethook_node *fpr; + int bit; if (!fp || fprobe_disabled(fp)) return; fpr = container_of(rh, struct fprobe_rethook_node, node); + /* we need to assure no calls to traceable functions in-between the + * end of fprobe_handler and the beginning of fprobe_exit_handler. + */ + bit = ftrace_test_recursion_trylock(fpr->entry_ip, fpr->entry_parent_ip); + if (bit < 0) { + fp->nmissed++; + return; + } + fp->exit_handler(fp, fpr->entry_ip, regs, fp->entry_data_size ? (void *)fpr->data : NULL); + ftrace_test_recursion_unlock(bit); } NOKPROBE_SYMBOL(fprobe_exit_handler); -- 2.40.1