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Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 Content-Language: en-US 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=2a00:1450:4864:20::533; envelope-from=thatlemon@gmail.com; helo=mail-ed1-x533.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, FREEMAIL_FROM=0.001, 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: , Cc: Peter Maydell , Richard Henderson , Laurent Vivier Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Some ELF binaries encode the .bss section as an extension of the data ones by setting the segment p_memsz > p_filesz. Some other binaries take a different route and encode it as a stand-alone PT_LOAD segment with p_filesz =3D 0 and p_memsz > 0. Both the encodings are actually correct per ELF specification but the ELF loader had some troubles in handling the former: with the old logic it was very likely to get Qemu to crash in zero_bss when trying to access unmapped memory. zero_bss isn't meant to allocate whole zero-filled segments but to "complete" a previously mapped segment with the needed zero bits. The fix is pretty simple, if the segment is completely zero-filled we simply allocate one or more pages (according to p_memsz) and avoid calling zero_bss altogether. Signed-off-by: Giuseppe Musacchio --- linux-user/elfload.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 0b02a92602..a16c240e0f 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2776,14 +2776,16 @@ static void load_elf_image(const char *image_name, = int image_fd, vaddr =3D load_bias + eppnt->p_vaddr; vaddr_po =3D TARGET_ELF_PAGEOFFSET(vaddr); vaddr_ps =3D TARGET_ELF_PAGESTART(vaddr); - vaddr_len =3D TARGET_ELF_PAGELENGTH(eppnt->p_filesz + vaddr_po= ); + + vaddr_ef =3D vaddr + eppnt->p_filesz; + vaddr_em =3D vaddr + eppnt->p_memsz; =20 /* - * Some segments may be completely empty without any backing f= ile - * segment, in that case just let zero_bss allocate an empty b= uffer - * for it. + * Some segments may be completely empty, with a non-zero p_me= msz + * but no backing file segment. */ if (eppnt->p_filesz !=3D 0) { + vaddr_len =3D TARGET_ELF_PAGELENGTH(eppnt->p_filesz + vadd= r_po); error =3D target_mmap(vaddr_ps, vaddr_len, elf_prot, MAP_PRIVATE | MAP_FIXED, image_fd, eppnt->p_offset - vaddr_po); @@ -2791,14 +2793,22 @@ static void load_elf_image(const char *image_name, = int image_fd, if (error =3D=3D -1) { goto exit_mmap; } - } =20 - vaddr_ef =3D vaddr + eppnt->p_filesz; - vaddr_em =3D vaddr + eppnt->p_memsz; + /* + * If the load segment requests extra zeros (e.g. bss), ma= p it. + */ + if (eppnt->p_filesz < eppnt->p_memsz) { + zero_bss(vaddr_ef, vaddr_em, elf_prot); + } + } else if (eppnt->p_memsz !=3D 0) { + vaddr_len =3D TARGET_ELF_PAGELENGTH(eppnt->p_memsz + vaddr= _po); + error =3D target_mmap(vaddr_ps, vaddr_len, elf_prot, + MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOU= S, + -1, 0); =20 - /* If the load segment requests extra zeros (e.g. bss), map it= . */ - if (vaddr_ef < vaddr_em) { - zero_bss(vaddr_ef, vaddr_em, elf_prot); + if (error =3D=3D -1) { + goto exit_mmap; + } } =20 /* Find the full program boundaries. */ --=20 2.29.2