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[76.251.165.188]) by smtp.gmail.com with ESMTPSA id h3sm6152625otr.4.2020.03.24.09.47.47 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 24 Mar 2020 09:47:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=i4y/hjStADTs4XYJUMM2HizGinURYTHFuzvbnc9AFAQ=; b=XJUqmdcldOcsxSNkBke8bWVrJmbn3fi+FeDOzYeQJvIeHcz98XbS3R/a0L/1MFMCDi Y8OQQe4KVWX108QauVKsKswEkObYeYcrM2JgkOl+j879YUBnUC7RbBu5IVe7Pp5wRPo/ KNZ07AaiAGktO685JMO9qxuTpGap/c9j+reSiLev5a2FZnSIEhbU6mQSjIoSe7LPrjr1 IHqP9sniZJoEiuc+zawbA7UB9GD46559ZcUFDV3doF45UldS/Wpc6w8gLweAhxJA+MQS doClOfmSMwbGLGkcZ38KkFa8fD+33hs0InluDiyA5xXYzw+QRDTnST7p3vkqDfoDAwFk V6nQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references; bh=i4y/hjStADTs4XYJUMM2HizGinURYTHFuzvbnc9AFAQ=; b=iw/MduJFHuIRgILBWngvyyiAvqoZzvz1TRI3m3eg3w1M3Hjni2ScBGrCyjCRDmMovh 8DB+heBlXt8/IC7wIgwepZwFXK/R/Gjq/NFRva/8EwzJE0mz2Em07MvGh1u96nmTlOE+ vi4RzdppLbt/1H0E2brhfKU9CQ7DMyaQrdIcbxDY2B1DVtm7H4HBl2f8Sotu9GHgMIAa wzLLkwh3wP6E3SVp1kjR81Yr7kk9qF6K95QfbyV/gtc9tq2nx1g4bbopU++Uw/mtLUHz A/vsVRp62CysO6KlycgTwsAfzHWYJVEldPfL5ONh6Triy1BTRjTY9XGcMZ8P9uYZRE6/ KPxQ== X-Gm-Message-State: ANhLgQ07WUNEE7Q8Cg5Fbs9o+Sw1vVDt8+jT6Eo0wXPi2GLX6FT+1VBG 0tDS/R3T9Mbg8sAgx3MZS1t5XQM9R4w= X-Google-Smtp-Source: ADFU+vufdZL/MRyTRsbOoGVRuzOO7vJb2ijvo/hqDzC+mgRSKjLTs2Vo70F14nJLmrEgxo48L/I0Ow== X-Received: by 2002:a9d:754e:: with SMTP id b14mr14718276otl.293.1585068468879; Tue, 24 Mar 2020 09:47:48 -0700 (PDT) From: Michael Roth To: qemu-devel@nongnu.org Subject: [PULL for-5.0 4/5] qga: Fix undefined C behavior Date: Tue, 24 Mar 2020 11:46:52 -0500 Message-Id: <20200324164653.19449-5-mdroth@linux.vnet.ibm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200324164653.19449-1-mdroth@linux.vnet.ibm.com> References: <20200324164653.19449-1-mdroth@linux.vnet.ibm.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::341 X-Mailman-Approved-At: Tue, 24 Mar 2020 13:24:20 -0400 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Eric Blake The QAPI struct GuestFileWhence has a comment about how we are exploiting equivalent values between two different integer types shared in a union. But C says behavior is undefined on assignments to overlapping storage when the two types are not the same width, and indeed, 'int64_t value' and 'enum QGASeek name' are very likely to be different in width. Utilize a temporary variable to fix things. Reported-by: Peter Maydell Fixes: 0b4b49387 Fixes: Coverity CID 1421990 Signed-off-by: Eric Blake Signed-off-by: Michael Roth --- qga/commands.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/qga/commands.c b/qga/commands.c index f8852beb9c..4471a9f08d 100644 --- a/qga/commands.c +++ b/qga/commands.c @@ -482,10 +482,15 @@ done: * the guest's SEEK_ constants. */ int ga_parse_whence(GuestFileWhence *whence, Error **errp) { - /* Exploit the fact that we picked values to match QGA_SEEK_*. */ + /* + * Exploit the fact that we picked values to match QGA_SEEK_*; + * however, we have to use a temporary variable since the union + * members may have different size. + */ if (whence->type =3D=3D QTYPE_QSTRING) { + int value =3D whence->u.name; whence->type =3D QTYPE_QNUM; - whence->u.value =3D whence->u.name; + whence->u.value =3D value; } switch (whence->u.value) { case QGA_SEEK_SET: --=20 2.17.1