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[96.19.192.232]) by smtp.gmail.com with ESMTPSA id l1sm2428699pjr.17.2020.05.02.09.12.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 May 2020 09:12:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=JLBfF7zcpENReJw9X1q5i9CqjijuEZErdvXJe3QU2rU=; b=LXEP2+/jyIIHn4yzxA/ltiOWwbz24/4uqbuFMwd+6nXpth+9L8A6tSG6h2DNJzgxT5 6mXf0hIVP7nucYpKXilKwfoXsJPgKmNcibZOY13qYeWGWD5eX6YqzSdNTfKwRb+5Vz5A M6gO9Bkg1Dew3mY8m1RGuu9CjlzAIzbW9bFJpnjQJsF63G3uMlss9vXV48zkyGWHML9I SMbmDLa4CqAf2DUYFcwJ1uPnr5HsG+3e3WeQ1vwPbFkEsL39341LRJ79Zi7yKbY0nrky JxfyWIXDMqXOuLaewpPguFEqvVGkH9IeU2lSNqTWy5OgKSEqs+aDPKDXVleY2uZeyQh5 XCtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=JLBfF7zcpENReJw9X1q5i9CqjijuEZErdvXJe3QU2rU=; b=aoyZywE4I8gd2oQB+7RRwOdDYQsBEeL4T50nOQlNZmswlP/zkdrg57w49MxKTawgco ui92LLxQwoEF90Ug0ezCrScnHHQSDlcQWXh2UT1IE76Bzndgdg2cmZyCecFRQ+wgkqco qM7+sl+nSz/U1dqwvzhLRfH8NXIvkF+PMXiec6YH4DYKHtHhoB/EVnGJpuvJBDE5XLDG aGh6iRIGUjktVnuMfbSpe5T6Ozzw3GEF8G39ZQGxLIykOSIz2i7r9pFO7G6m8ilYzL2z 9LKtuiAEUcfIelzubLWMyVQrobS3LqqhK8wblKuYb/MUm4It9N2FuBCrT4UEsWopeY1j 6bZg== X-Gm-Message-State: AGi0PuYj7pQUApIFezwi8SHVoLGsWk0pk6YnTbLk4xpknDwTr8YbFdCD MOi3JPs1xy7h4b+it6+egbvk4KiNLQzW3+4h X-Google-Smtp-Source: APiQypImDf+TdZl/sSLTn4POU1LEo9bj/sDcHg737bVbGe959z82HXYm7LFFAByDHrPsPlyAWhRugA== X-Received: by 2002:a63:4c9:: with SMTP id 192mr9468736pge.207.1588435958952; Sat, 02 May 2020 09:12:38 -0700 (PDT) From: Jonathan Marler To: qemu-devel@nongnu.org Subject: [PATCH] linux-user/mmap.c: fix integer underflow in target_mremap Date: Sat, 2 May 2020 10:12:25 -0600 Message-Id: <20200502161225.14346-1-johnnymarler@gmail.com> X-Mailer: git-send-email 2.23.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:20::544; envelope-from=johnnymarler@gmail.com; helo=mail-pg1-x544.google.com X-detected-operating-system: by eggs.gnu.org: Error: [-] PROGRAM ABORT : Malformed IPv6 address (bad octet value). Location : parse_addr6(), p0f-client.c:67 X-Received-From: 2607:f8b0:4864:20::544 X-Mailman-Approved-At: Sat, 02 May 2020 12:52:16 -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: Jonathan Marler Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @gmail.com) Content-Type: text/plain; charset="utf-8" Fixes: https://bugs.launchpad.net/bugs/1876373 This code path in mmap occurs when a page size is decreased with mremap. W= hen a section of pages is shrunk, qemu calls mmap_reserve on the pages that= were released. However, it has the diff operation reversed, subtracting t= he larger old_size from the smaller new_size. Instead, it should be subtra= cting the smaller new_size from the larger old_size. You can also see in t= he previous line of the change that this mmap_reserve call only occurs when= old_size > new_size. Signed-off-by: Jonathan Marler Reviewed-by: Laurent Vivier --- linux-user/mmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/linux-user/mmap.c b/linux-user/mmap.c index e378033797..caab62909e 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -708,7 +708,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong ol= d_size, if (prot =3D=3D 0) { host_addr =3D mremap(g2h(old_addr), old_size, new_size, flags); if (host_addr !=3D MAP_FAILED && reserved_va && old_size > new= _size) { - mmap_reserve(old_addr + old_size, new_size - old_size); + mmap_reserve(old_addr + old_size, old_size - new_size); } } else { errno =3D ENOMEM; --=20 2.23.1