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([2001:8b0:aba:5f3c:8262:2156:a38b:824c]) by smtp.gmail.com with ESMTPSA id k6sm13076265wmf.25.2021.01.08.09.42.13 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Jan 2021 09:42:13 -0800 (PST) Message-ID: <70c46e7b999bafbb01d54bfafd44b420d0b782e9.camel@linuxfoundation.org> Subject: [PATCH] linux-user/mmap: Avoid asserts for out of range mremap calls From: Richard Purdie To: "qemu-devel@nongnu.org" Date: Fri, 08 Jan 2021 17:42:12 +0000 User-Agent: Evolution 3.38.1-1 MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::42e; envelope-from=richard.purdie@linuxfoundation.org; helo=mail-wr1-x42e.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: 2.1.23 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" If mremap() is called without the MREMAP_MAYMOVE flag with a start address just before the end of memory (reserved_va) where new_size would exceed it (and GUEST_ADDR_MAX), the assert(end - 1 <= GUEST_ADDR_MAX) in  page_set_flags() would trigger. Add an extra guard to the guest_range_valid() checks to prevent this and avoid asserting binaries when reserved_va is set. This meant a bug I was seeing locally now gives the same behaviour  regardless of whether reserved_va is set or not. Signed-off-by: Richard Purdie Index: qemu-5.2.0/linux-user/mmap.c =================================================================== --- qemu-5.2.0.orig/linux-user/mmap.c +++ qemu-5.2.0/linux-user/mmap.c @@ -727,7 +727,9 @@ abi_long target_mremap(abi_ulong old_add if (!guest_range_valid(old_addr, old_size) || ((flags & MREMAP_FIXED) && - !guest_range_valid(new_addr, new_size))) { + !guest_range_valid(new_addr, new_size)) || + ((flags & MREMAP_MAYMOVE) == 0 && + !guest_range_valid(old_addr, new_size))) { errno = ENOMEM; return -1; }