[{"id":3678752,"web_url":"http://patchwork.ozlabs.org/comment/3678752/","msgid":"<87mrz1k5w7.fsf@pond.sub.org>","list_archive_url":null,"date":"2026-04-17T14:39:36","subject":"Re: [PATCH] system: Improve error handling and robustness","submitter":{"id":2645,"url":"http://patchwork.ozlabs.org/api/people/2645/","name":"Markus Armbruster","email":"armbru@redhat.com"},"content":"Jun Yu writes:\n\n> This commit fixes two important issues:\n>\n> 1. In parse_name(), ensure qemu_name is never NULL by initializing it to\n> an empty string when the \"guest\" option is not provided. This prevents\n> potential null pointer dereferences.\n\nCan you point to an actual null pointer dereference?\n\nIf you can't, there is no bug to fix.\n\nIf you can, then your fix needs work. Here's why.\n\nparse_name() runs when the user passes a -name option. Your patch\nensures parse_name sets @qemu_name to a non-null string.\n\nWhen it doesn't run, @qemu_name remains null.\n\nThe users of qemu_name check whether it is null. For instance:\n\n const char *audio_application_name(void)\n {\n const char *vm_name;\n\n vm_name = qemu_get_vm_name();\n return vm_name ? vm_name : \"qemu\";\n }\n\nYour patch breaks such code when -name is passed.\n\n> 2. In parse_add_fd(), replace error_abort with proper error handling\n> using the provided errp parameter. This avoids immediate program\n> termination on failure and allows for more graceful error reporting.\n\nThis is insufficient rationale.\n\n&error_abort is a fancy way to write assert(). It's is the appropriate\nway to catch programming errors, i.e. errors that aren't supposed to\nhappen, and when they do happen, there is a bug that needs fixing.\n\nYou'd have to explain why this error is *not* a programming error. As a\nfirst step, explain how it could happen.\n\nYou can't, because it is in fact a programming error.\nmonitor_fdset_add_fd() only fails when passed a an @fdset_id < 0.\nparse_add_fd() catches that itself a few lines above the call.\n\n> These changes improve the robustness of the QEMU system emulator by\n> providing more predictable error handling and preventing potential\n> crashes.\n\nThis sounds like an AI to me. Please note that current QEMU project\npolicy is to DECLINE any contributions which are believed to include or\nderive from AI generated content. See docs/devel/code-provenance.rst\nsection \"Use of AI-generated content\" for why.\n\n> Signed-off-by: Jun Yu \n> ---\n> system/vl.c | 9 ++++++++-\n> 1 file changed, 8 insertions(+), 1 deletion(-)\n>\n> diff --git a/system/vl.c b/system/vl.c\n> index 246623b319..eb07b04044 100644\n> --- a/system/vl.c\n> +++ b/system/vl.c\n> @@ -560,6 +560,9 @@ static int parse_name(void *opaque, QemuOpts *opts, Error **errp)\n> }\n> \n> qemu_name = qemu_opt_get(opts, \"guest\");\n> + if (!qemu_name) {\n> + qemu_name = \"\";\n> + }\n> \n> proc_name = qemu_opt_get(opts, \"process\");\n> if (proc_name) {\n> @@ -626,7 +629,11 @@ static int parse_add_fd(void *opaque, QemuOpts *opts, Error **errp)\n> \n> /* add the duplicate fd, and optionally the opaque string, to the fd set */\n> fdinfo = monitor_fdset_add_fd(dupfd, true, fdset_id, fd_opaque,\n> - &error_abort);\n> + errp);\n> + if (!fdinfo) {\n> + close(dupfd);\n> + return -1;\n> + }\n> g_free(fdinfo);\n> \n> return 0;","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=NMJAkGDV;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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Fri, 17 Apr 2026 16:39:36 +0200 (CEST)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1776436784;\n h=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n to:to:cc:cc:mime-version:mime-version:content-type:content-type:\n in-reply-to:in-reply-to:references:references;\n bh=u2H6ont24s/tEJdHct1r+q8YkBP2G1W56q9PhJOwKjU=;\n b=NMJAkGDVcIJHrANbdot/YA+B93drbiimCQ/xoVIJ5SsRkvcP1Vr1nqilFHTYDj5JXdFOze\n Cp4lOJIdMpJrKeFXVS+oyaXSwGhm6g+PeFSXXLXgGveceSXiN6OOJcEHNLiiUeshhHWX7s\n WdBUwfP0gdVOGe36eDsAJSBmE39tYnw=","X-MC-Unique":"tcQrB4tHOCOigZ3R2kWP_g-1","X-Mimecast-MFC-AGG-ID":"tcQrB4tHOCOigZ3R2kWP_g_1776436780","From":"Markus Armbruster ","To":"Jun Yu ","Cc":"pbonzini@redhat.com, qemu-devel@nongnu.org","Subject":"Re: [PATCH] system: Improve error handling and robustness","In-Reply-To":"<20260408022507.27457-1-yujun@kylinos.cn> (Jun Yu's message of\n \"Wed, 8 Apr 2026 10:25:07 +0800\")","References":"<20260408022507.27457-1-yujun@kylinos.cn>","Date":"Fri, 17 Apr 2026 16:39:36 +0200","Message-ID":"<87mrz1k5w7.fsf@pond.sub.org>","User-Agent":"Gnus/5.13 (Gnus v5.13)","MIME-Version":"1.0","Content-Type":"text/plain","X-Scanned-By":"MIMEDefang 3.0 on 10.30.177.17","Received-SPF":"pass client-ip=170.10.129.124; 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