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[88.187.86.199]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-447f38142f1sm243665085e9.31.2025.05.26.11.10.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 May 2025 11:10:57 -0700 (PDT) Message-ID: <3a7386f9-a4ba-4268-a3fe-45c18360d878@linaro.org> Date: Mon, 26 May 2025 20:10:56 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] hw/xen: Fix trace_xs_node_read() params To: Liam Merwick , dwmw@amazon.co.uk, anthony.perard@vates.tech, roger.pau@citrix.com, xen-devel@lists.xenproject.org, qemu-devel@nongnu.org References: <20250523160134.218997-1-liam.merwick@oracle.com> Content-Language: en-US From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= In-Reply-To: <20250523160134.218997-1-liam.merwick@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::32f; envelope-from=philmd@linaro.org; helo=mail-wm1-x32f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 23/5/25 18:01, Liam Merwick wrote: > When the '--enable-trace-backends=syslog' build option is configured, > the following compilation error is encountered. > > In file included from /usr/include/sys/syslog.h:207, > from /usr/include/syslog.h:1, > from ./trace/trace-hw_xen.h:224, > from ../hw/xen/trace.h:1, > from ../hw/xen/xen-bus-helper.c:13: > In function ‘syslog’, > inlined from ‘_nocheck__trace_xs_node_read’ at ../hw/xen/trace-events:41:9, > inlined from ‘trace_xs_node_read’ at trace/trace-hw_xen.h:903:9, > inlined from ‘xs_node_read’ at ../hw/xen/xen-bus-helper.c:154:5: > /usr/include/bits/syslog.h:45:3: error: ‘%s’ directive argument is null [-Werror=format-overflow=] > 45 | __syslog_chk (__pri, __USE_FORTIFY_LEVEL - 1, __fmt, __va_arg_pack ()); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Add a check that 'value' is not null before passing it to trace_xs_node_read(). > > Fixes: e6cdeee95990 ("hw/xen: Add xs_node_read() helper function") > Signed-off-by: Liam Merwick > --- > hw/xen/xen-bus-helper.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/hw/xen/xen-bus-helper.c b/hw/xen/xen-bus-helper.c > index 288fad422be3..1087a585cc71 100644 > --- a/hw/xen/xen-bus-helper.c > +++ b/hw/xen/xen-bus-helper.c > @@ -151,7 +151,7 @@ char *xs_node_read(struct qemu_xs_handle *h, xs_transaction_t tid, > va_end(ap); > > value = qemu_xen_xs_read(h, tid, path, len); > - trace_xs_node_read(path, value); > + trace_xs_node_read(path, value ? value : ""); > if (!value) { > error_setg_errno(errp, errno, "failed to read from '%s'", path); > } Alternatively, since this is an error path: -- >8 -- diff --git a/hw/xen/xen-bus-helper.c b/hw/xen/xen-bus-helper.c index 288fad422be..1e49e60e147 100644 --- a/hw/xen/xen-bus-helper.c +++ b/hw/xen/xen-bus-helper.c @@ -143,7 +143,8 @@ char *xs_node_read(struct qemu_xs_handle *h, xs_transaction_t tid, unsigned int *len, Error **errp, const char *path_fmt, ...) { - char *path, *value; + g_autofree char *value; + char *path; va_list ap; va_start(ap, path_fmt); @@ -151,12 +152,11 @@ char *xs_node_read(struct qemu_xs_handle *h, xs_transaction_t tid, va_end(ap); value = qemu_xen_xs_read(h, tid, path, len); - trace_xs_node_read(path, value); if (!value) { error_setg_errno(errp, errno, "failed to read from '%s'", path); + return NULL; } - - g_free(path); + trace_xs_node_read(path, value); return value; } --- But your patch isn't wrong, so: Reviewed-by: Philippe Mathieu-Daudé