On Tue, Apr 25, 2017 at 02:58:01PM +0800, dongbo (E) wrote: > From: Dong Bo <dongbo4@xxxxxxxxxx> > > In load_elf_binary(), once the READ_IMPLIES_EXEC flag is set, > the flag is propagated to its child processes, even the elf > files are marked as not requiring executable stack. It may > cause superfluous operations on some arch, e.g. > __sync_icache_dcache on aarch64 due to a PROT_READ mmap is > also marked as PROT_EXEC. > > This patch was originally posted and discussed here: > https://patchwork.kernel.org/patch/9685891/ > > Signed-off-by: Dong Bo <dongbo4@xxxxxxxxxx> > --- > fs/binfmt_elf.c | 2 ++ > fs/binfmt_elf_fdpic.c | 2 ++ > 2 files changed, 4 insertions(+) > > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > index 5075fd5..c52e670 100644 > --- a/fs/binfmt_elf.c > +++ b/fs/binfmt_elf.c > @@ -863,6 +863,8 @@ static int load_elf_binary(struct linux_binprm *bprm) > SET_PERSONALITY2(loc->elf_ex, &arch_state); > if (elf_read_implies_exec(loc->elf_ex, executable_stack)) > current->personality |= READ_IMPLIES_EXEC; > + else > + current->personality &= ~READ_IMPLIES_EXEC; > if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) > current->flags |= PF_RANDOMIZE; > diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c > index cf93a4f..c4bc4d0 100644 > --- a/fs/binfmt_elf_fdpic.c > +++ b/fs/binfmt_elf_fdpic.c > @@ -354,6 +354,8 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm) > set_personality(PER_LINUX); > if (elf_read_implies_exec(&exec_params.hdr, executable_stack)) > current->personality |= READ_IMPLIES_EXEC; > + else > + current->personality &= ~READ_IMPLIES_EXEC; > setup_new_exec(bprm); > -- 1.9.1 FWIW, we queued the arm64-equivalent patch (commit 48f99c8ec0b25 in linux-next). It doesn't change the behaviour for compat tasks since we want to keep the same behaviour with arch/arm. If the above generic patch gets merged, we'll drop the arm64-specific one. -- Catalin
