From d87146bce08d3d2ea6c00025d7ee0bfa77991692 Mon Sep 17 00:00:00 2001 From: Giuseppe Musacchio Date: Fri, 3 May 2019 14:20:07 +0200 Subject: [PATCH] linux-user: elf: Map empty PT_LOAD segments Some PT_LOAD segments may be completely zeroed out and their p_filesize is zero, in that case the loader should just allocate a page that's at least p_memsz bytes large (plus eventual alignment padding). Calling zero_bss does this job for us, all we have to do is make sure we don't try to mmap a zero-length page. Signed-off-by: Giuseppe Musacchio Reviewed-by: Peter Maydell Message-Id: <20190503122007.lkjsvztgt4ycovac@debian> Signed-off-by: Laurent Vivier --- linux-user/elfload.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index d08fe23466..ef42e02d82 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2366,11 +2366,19 @@ static void load_elf_image(const char *image_name, int image_fd, vaddr_ps = TARGET_ELF_PAGESTART(vaddr); vaddr_len = TARGET_ELF_PAGELENGTH(eppnt->p_filesz + vaddr_po); - error = target_mmap(vaddr_ps, vaddr_len, - elf_prot, MAP_PRIVATE | MAP_FIXED, - image_fd, eppnt->p_offset - vaddr_po); - if (error == -1) { - goto exit_perror; + /* + * Some segments may be completely empty without any backing file + * segment, in that case just let zero_bss allocate an empty buffer + * for it. + */ + if (eppnt->p_filesz != 0) { + error = target_mmap(vaddr_ps, vaddr_len, elf_prot, + MAP_PRIVATE | MAP_FIXED, + image_fd, eppnt->p_offset - vaddr_po); + + if (error == -1) { + goto exit_perror; + } } vaddr_ef = vaddr + eppnt->p_filesz;