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[81.40.121.39]) by smtp.gmail.com with ESMTPSA id u6sm5916876wml.23.2021.04.14.05.16.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 Apr 2021 05:16:44 -0700 (PDT) Subject: Re: [PATCH] hw/elf_ops: clear uninitialized segment space To: Laurent Vivier , qemu-devel@nongnu.org References: <20210414105838.205019-1-laurent@vivier.eu> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: Date: Wed, 14 Apr 2021 14:16:43 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210414105838.205019-1-laurent@vivier.eu> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2a00:1450:4864:20::430; envelope-from=philippe.mathieu.daude@gmail.com; helo=mail-wr1-x430.google.com X-Spam_score_int: -14 X-Spam_score: -1.5 X-Spam_bar: - X-Spam_report: (-1.5 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.25, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no 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: , Cc: Peter Maydell , Stefano Garzarella Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 4/14/21 12:58 PM, Laurent Vivier wrote: > When the mem_size of the segment is bigger than the file_size, > and if this space doesn't overlap another segment, it needs > to be cleared. > > This bug is very similar to the one we had for linux-user, > 22d113b52f41 ("linux-user: Fix loading of BSS segments"), > where .bss section is encoded as an extension of the the data > one by setting the segment p_memsz > p_filesz. > > Signed-off-by: Laurent Vivier > --- > include/hw/elf_ops.h | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h > index 6ee458e7bc3c..e3dcee3ee349 100644 > --- a/include/hw/elf_ops.h > +++ b/include/hw/elf_ops.h > @@ -562,6 +562,23 @@ static int glue(load_elf, SZ)(const char *name, int fd, > if (res != MEMTX_OK) { > goto fail; > } > + /* > + * We need to zero'ify the space that is not copied > + * from file > + */ > + if (file_size < mem_size) { > + static uint8_t zero[4096]; Given it is unlikely, maybe better use: g_autofree uint8_t *zero = g_new0(uint8_t, 4096); > + uint64_t i; > + for (i = file_size; i < mem_size; i += sizeof(zero)) { > + res = address_space_write( > + as ? as : &address_space_memory, > + addr + i, MEMTXATTRS_UNSPECIFIED, > + zero, MIN(sizeof(zero), mem_size - i)); > + if (res != MEMTX_OK) { > + goto fail; > + } > + } > + } > } > } > >