From: Franck Bui-Huu Date: Wed, 17 Oct 2007 06:30:24 +0000 (-0700) Subject: Break ELF_PLATFORM and stack pointer randomization dependency X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d68c9d6ae8f1fdae7d998158adc5ee106a2f8ce6;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git Break ELF_PLATFORM and stack pointer randomization dependency Currently arch_align_stack() is used by fs/binfmt_elf.c to randomize stack pointer inside a page. But this happens only if ELF_PLATFORM symbol is defined. ELF_PLATFORM is normally set if the architecture wants ld.so to load implementation specific libraries for optimization. And currently a lot of architectures just yield this symbol to NULL. This is the case for MIPS architecture where ELF_PLATFORM is NULL but arch_align_stack() has been redefined to do stack inside page randomization. So in this case no randomization is actually done. This patch breaks this dependency which seems to be useless and allows platforms such MIPS to do the randomization. Signed-off-by: Franck Bui-Huu Cc: Ingo Molnar Cc: Arjan van de Ven Cc: Ralf Baechle Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 0f55b71ed983..6e2f3b8dde7f 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -150,6 +150,14 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, struct task_struct *tsk = current; struct vm_area_struct *vma; + /* + * In some cases (e.g. Hyper-Threading), we want to avoid L1 + * evictions by the processes running on the same package. One + * thing we can do is to shuffle the initial stack for them. + */ + + p = arch_align_stack(p); + /* * If this architecture has a platform capability string, copy it * to userspace. In some cases (Sparc), this info is impossible @@ -160,14 +168,6 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, if (k_platform) { size_t len = strlen(k_platform) + 1; - /* - * In some cases (e.g. Hyper-Threading), we want to avoid L1 - * evictions by the processes running on the same package. One - * thing we can do is to shuffle the initial stack for them. - */ - - p = arch_align_stack(p); - u_platform = (elf_addr_t __user *)STACK_ALLOC(p, len); if (__copy_to_user(u_platform, k_platform, len)) return -EFAULT;