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[104.15.236.76]) by smtp.googlemail.com with ESMTPSA id 00721157ae682-6e2d926b44esm20294217b3.16.2024.10.09.15.06.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Oct 2024 15:06:58 -0700 (PDT) From: Tyrone Wu To: bpf@vger.kernel.org, wudevelops@gmail.com Cc: kpsingh@kernel.org, mattbobrowski@google.com, song@kernel.org, jolsa@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, yonghong.song@linux.dev, john.fastabend@gmail.com, sdf@fomichev.me, haoluo@google.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, mykolal@fb.com, shuah@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-patches-bot@fb.com Subject: [PATCH bpf v1 1/2] bpf: fix unpopulated path_size when uprobe_multi fields unset Date: Wed, 9 Oct 2024 22:06:37 +0000 Message-ID: <20241009220638.333429-1-wudevelops@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Previously when retrieving `bpf_link_info.uprobe_multi` with `path` and `path_size` fields unset, the `path_size` field is not populated (remains 0). This behavior was inconsistent with how other input/output string buffer fields work, as the field should be populated in cases when: - both buffer and length are set (currently works as expected) - both buffer and length are unset (not working as expected) This patch now fills the `path_size` field when `path` and `path_size` are unset. Fixes: e56fdbfb06e2 ("bpf: Add link_info support for uprobe multi link") Signed-off-by: Tyrone Wu --- kernel/trace/bpf_trace.c | 35 +++++++++++++++++------------------ 1 file changed, 17 insertions(+), 18 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index a582cd25ca87..ba34e4f3fa8f 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3133,7 +3133,8 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link, struct bpf_uprobe_multi_link *umulti_link; u32 ucount = info->uprobe_multi.count; int err = 0, i; - long left; + char *p, *buf; + long left = 0; if (!upath ^ !upath_size) return -EINVAL; @@ -3147,26 +3148,24 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link, info->uprobe_multi.pid = umulti_link->task ? task_pid_nr_ns(umulti_link->task, task_active_pid_ns(current)) : 0; - if (upath) { - char *p, *buf; - - upath_size = min_t(u32, upath_size, PATH_MAX); + upath_size = upath_size ? min_t(u32, upath_size, PATH_MAX) : PATH_MAX; + buf = kmalloc(upath_size, GFP_KERNEL); + if (!buf) + return -ENOMEM; + p = d_path(&umulti_link->path, buf, upath_size); + if (IS_ERR(p)) { + kfree(buf); + return PTR_ERR(p); + } + upath_size = buf + upath_size - p; - buf = kmalloc(upath_size, GFP_KERNEL); - if (!buf) - return -ENOMEM; - p = d_path(&umulti_link->path, buf, upath_size); - if (IS_ERR(p)) { - kfree(buf); - return PTR_ERR(p); - } - upath_size = buf + upath_size - p; + if (upath) { left = copy_to_user(upath, p, upath_size); - kfree(buf); - if (left) - return -EFAULT; - info->uprobe_multi.path_size = upath_size; } + kfree(buf); + if (left) + return -EFAULT; + info->uprobe_multi.path_size = upath_size; if (!uoffsets && !ucookies && !uref_ctr_offsets) return 0;