The elf-fdpic loader hard sets the process personality to either PER_LINUX_FDPIC for true elf-fdpic binaries or to PER_LINUX for normal ELF binaries (in this case they would be constant displacement compiled with -pie for example). The problem with that is that it will lose any other bits that may be in the ELF header personality (such as the "bug emulation" bits). On the ARM architecture the ADDR_LIMIT_32BIT flag is used to signify a normal 32bit binary - as opposed to a legacy 26bit address binary. This matters since start_thread() will set the ARM CPSR register as required based on this flag. If the elf-fdpic loader loses this bit the process will be mis-configured and crash out pretty quickly. Modify elf-fdpic loaders personality setting for ELF binaries so that it preserves the upper three bytes by using the SET_PERSONALITY macro to set it. This macro in the generic case sets PER_LINUX but and preserves the upper bytes. Architectures can override this for their specific use case, and ARM does exactly this. Signed-off-by: Greg Ungerer <gerg@xxxxxxxxxx> --- Is anyone out there using elf-fdpic on ARM? This seems to break it rather badly due to the loss of that ADDR_LIMIT_32BIT bit from the process personality. fs/binfmt_elf_fdpic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index a05eafcacfb2..f29ae1d96fd7 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -348,7 +348,7 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm) if (elf_check_fdpic(&exec_params.hdr)) set_personality(PER_LINUX_FDPIC); else - set_personality(PER_LINUX); + SET_PERSONALITY(exec_params.hdr); if (elf_read_implies_exec(&exec_params.hdr, executable_stack)) current->personality |= READ_IMPLIES_EXEC; -- 2.25.1
