From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ED21237DE84 for ; Fri, 10 Jul 2026 18:35:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783708525; cv=none; b=dJJSFTsOmIXHzjibuFMPH7BQ6+cXt/bdcjpVTGjRGtqAucICd4BAvVX7uv4aknRTG3XpkfejID3AxCtuVuuROilmLf2W/trG7TLmiJ+pOVqehj/JNr803c1bduj8yz5H+m8lIKhPBrELa1UP158GjDJA8ytpQwQkdBnRfWvce1A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783708525; c=relaxed/simple; bh=cVwSutYXyxu2kAs+M/fqvlMTLCP40ylY2LRCvNSraqE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=jriq2oYZaU8/Cb1gjTsVEWg6SjW0GHKs4edla1oK3t3RnkLtGify1Yn4zQAvv20KynmPdQPyDmxPxL++fzU1/FrfCBxdl9zSwLu/pMNasSmQLJizWre6xq0TKoWmEMWbRL3pdschM9zckZ/ojTLalm/CkLAIHMVXV43sqYV1JGs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=Av65lYSB; arc=none smtp.client-ip=209.85.210.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Av65lYSB" Received: by mail-pf1-f202.google.com with SMTP id d2e1a72fcca58-8482b95574dso1307352b3a.1 for ; Fri, 10 Jul 2026 11:35:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1783708522; x=1784313322; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=wJss+Nyx//3KxfsXosZCusg05vSosR0BprDgk0IeJw4=; b=Av65lYSBQw5YZgD7X1tlREBGFmfcfSzmXSmXNbSipPRfOoVzgZ8tT4eWFNDfnEqZx8 E2D4XIFP81YL+6HPZKfsCffX08KSk+8HukobTYCE7OB+3DssiT1gr/7BElI4WdiHoLpn EGhP9RMkupEUIMs6ahit/WOTxf5tVMTwv9Bx2/LOoMNLPSYwghJro5qYV59Yq6pqGDSc vX7Fm+Kb3YBIMVAnSqgNTrbC9bhKpTL3W95//vNw7ua3n8lcMT/bAFcg2qKdCnNXQNse J5bDcyrNuSVr6I6ytfPcHO2xUejCvn1yrrcdooNCZOdBkRLfbr5Lvrk1hhvFvOAU5pe6 VtQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783708522; x=1784313322; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=wJss+Nyx//3KxfsXosZCusg05vSosR0BprDgk0IeJw4=; b=QZkfVGmOSe6JcKntuQuNJRcBPmhNZX8dKFxdbXOTwhRR9cfGZ3Wy9kwtqUF0VGMjCD AD/GO0Uab2JnnQxmu4TJ8Zj9qrFEGIkP4HY9aPYKJirMuExy1+pK6rym3CE0BK01DIEs IsRpgDrmk6vNl+N9+sVbcjJB5hCk12vBdOQX25EWr9T+1CO+0OkuzbSwGBDUwWpoXa9j sFfD1VDrUJfcUMJx2PIP+tRg1bVBuiZDqbvM5Boucxgx9hvYPirMp31UaW8ho3HRY9Ta 7JYaocxllWzttMYsoR++3BMTMGkvCELJXQKtVkQcd9a+AXLnRdceL/j+h9Wg7hH2sTEy 5afw== X-Forwarded-Encrypted: i=1; AHgh+RpSmObcxZzQDQTIDMg1kbLZ70IQ/uNjG5NfI+3yC5gTvhB2eWhgZZrFc97tFDWDb6zd3+I=@vger.kernel.org X-Gm-Message-State: AOJu0YyR4yH7GNYon5mjEEivEhAkz4IxDy194BcEvOKjtx4/OFs6UQiT oew8C0kskTEW8CEBecx7bmIhhsp17szXLPWHoez+iGFAKd07pP+/C4O/hsKbVj4tef6kA0NIaaq SxPscJA== X-Received: from pfdb8.prod.google.com ([2002:a05:6a00:94e8:b0:847:878f:44fd]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:3cd4:b0:847:712d:19ac with SMTP id d2e1a72fcca58-84889637560mr217734b3a.8.1783708522009; Fri, 10 Jul 2026 11:35:22 -0700 (PDT) Date: Fri, 10 Jul 2026 11:35:21 -0700 In-Reply-To: <20260710135312.AD74F1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260710134055.16432-1-danielpaziyski@gmail.com> <20260710135312.AD74F1F000E9@smtp.kernel.org> Message-ID: Subject: Re: [PATCH] KVM: x86: Fix null pointer dereference in trace_kvm_inj_exception From: Sean Christopherson To: sashiko-reviews@lists.linux.dev Cc: Daniel Paziyski , kvm@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Fri, Jul 10, 2026, sashiko-bot@kernel.org wrote: > > An empty struct is being passed, which makes the > > kernel derefence a NULL pointer when the error code is 0. Remove this > > stray struct in the invocation of __print_symbolic. > > [Severity: Medium] > Is this description of a null pointer dereference accurate? Yes, it is. Sashiko apparently applied to an old base (pre-7.1). As of commit 754e38d2d1ae ("tracing: Use explicit array size instead of sentinel elements in symbol printing") (spoiler alert), trace_print_symbols_seq() is: for (i = 0; i < symbol_array_size; i++) { if (val != symbol_array[i].mask) continue; trace_seq_puts(p, symbol_array[i].name); break; } > Looking at how __print_symbolic expands, the empty struct { } safely > initializes the first element's name pointer to NULL. When > trace_print_symbols_seq() is called, it handles this gracefully: > > kernel/trace/trace_output.c:trace_print_symbols_seq() { > ... > for (i = 0; symbol_array[i].name; i++) { > ... > } > > Since the name field is NULL for the first element, the loop is bypassed > entirely and the function safely falls back to printing the error code as a > hex string without dereferencing a NULL pointer. > > > diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h > > --- a/arch/x86/kvm/trace.h > > +++ b/arch/x86/kvm/trace.h > > @@ -490,7 +490,7 @@ TRACE_EVENT(kvm_inj_exception, > > TP_printk("%s%s%s%s%s", > > __print_symbolic(__entry->exception, kvm_trace_sym_exc), > > !__entry->has_error ? "" : " (", > > - !__entry->has_error ? "" : __print_symbolic(__entry->error_code, { }), > > + !__entry->has_error ? "" : __print_symbolic(__entry->error_code), > > [Severity: Low] > Will this change break the kernel build? No, beacuse again, Sashiko applied to an old base for some reason.