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Commit 221af7f8 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Split 'flush_old_exec' into two functions 



'flush_old_exec()' is the point of no return when doing an execve(), and
it is pretty badly misnamed.  It doesn't just flush the old executable
environment, it also starts up the new one.

Which is very inconvenient for things like setting up the new
personality, because we want the new personality to affect the starting
of the new environment, but at the same time we do _not_ want the new
personality to take effect if flushing the old one fails.

As a result, the x86-64 '32-bit' personality is actually done using this
insane "I'm going to change the ABI, but I haven't done it yet" bit
(TIF_ABI_PENDING), with SET_PERSONALITY() not actually setting the
personality, but just the "pending" bit, so that "flush_thread()" can do
the actual personality magic.

This patch in no way changes any of that insanity, but it does split the
'flush_old_exec()' function up into a preparatory part that can fail
(still called flush_old_exec()), and a new part that will actually set
up the new exec environment (setup_new_exec()).  All callers are changed
to trivially comply with the new world order.

Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
Cc: stable@kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 64a028a6

arch/sh/kernel/process_64.c

+1 −1
Original line number Diff line number Diff line
@@ -368,7 +368,7 @@ void exit_thread(void) 
void flush_thread(void)

{



	/* Called by fs/exec.c (flush_old_exec) to remove traces of a

	/* Called by fs/exec.c (setup_new_exec) to remove traces of a

	 * previously running executable. */

#ifdef CONFIG_SH_FPU

	if (last_task_used_math == current) {

arch/x86/ia32/ia32_aout.c

+6 −4
Original line number Diff line number Diff line
@@ -308,15 +308,17 @@ static int load_aout_binary(struct linux_binprm *bprm, struct pt_regs *regs) 
	if (retval)

		return retval;



	regs->cs = __USER32_CS;

	regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =

		regs->r13 = regs->r14 = regs->r15 = 0;



	/* OK, This is the point of no return */

	set_personality(PER_LINUX);

	set_thread_flag(TIF_IA32);

	clear_thread_flag(TIF_ABI_PENDING);



	setup_new_exec(bprm);



	regs->cs = __USER32_CS;

	regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =

		regs->r13 = regs->r14 = regs->r15 = 0;



	current->mm->end_code = ex.a_text +

		(current->mm->start_code = N_TXTADDR(ex));

	current->mm->end_data = ex.a_data +

fs/binfmt_aout.c

+1 −0
Original line number Diff line number Diff line
@@ -264,6 +264,7 @@ static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs) 
#else

	set_personality(PER_LINUX);

#endif

	setup_new_exec(bprm);



	current->mm->end_code = ex.a_text +

		(current->mm->start_code = N_TXTADDR(ex));

fs/binfmt_elf.c

+2 −25
Original line number Diff line number Diff line
@@ -662,27 +662,6 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 
			if (elf_interpreter[elf_ppnt->p_filesz - 1] != '\0')

				goto out_free_interp;



			/*

			 * The early SET_PERSONALITY here is so that the lookup

			 * for the interpreter happens in the namespace of the 

			 * to-be-execed image.  SET_PERSONALITY can select an

			 * alternate root.

			 *

			 * However, SET_PERSONALITY is NOT allowed to switch

			 * this task into the new images's memory mapping

			 * policy - that is, TASK_SIZE must still evaluate to

			 * that which is appropriate to the execing application.

			 * This is because exit_mmap() needs to have TASK_SIZE

			 * evaluate to the size of the old image.

			 *

			 * So if (say) a 64-bit application is execing a 32-bit

			 * application it is the architecture's responsibility

			 * to defer changing the value of TASK_SIZE until the

			 * switch really is going to happen - do this in

			 * flush_thread().	- akpm

			 */

			SET_PERSONALITY(loc->elf_ex);



			interpreter = open_exec(elf_interpreter);

			retval = PTR_ERR(interpreter);

			if (IS_ERR(interpreter))
@@ -730,9 +709,6 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 
		/* Verify the interpreter has a valid arch */

		if (!elf_check_arch(&loc->interp_elf_ex))

			goto out_free_dentry;

	} else {

		/* Executables without an interpreter also need a personality  */

		SET_PERSONALITY(loc->elf_ex);

	}



	/* Flush all traces of the currently running executable */
@@ -752,7 +728,8 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 


	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)

		current->flags |= PF_RANDOMIZE;

	arch_pick_mmap_layout(current->mm);



	setup_new_exec(bprm);



	/* Do this so that we can load the interpreter, if need be.  We will

	   change some of these later */

fs/binfmt_elf_fdpic.c

+3 −0
Original line number Diff line number Diff line
@@ -321,6 +321,9 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm, 
	set_personality(PER_LINUX_FDPIC);

	if (elf_read_implies_exec(&exec_params.hdr, executable_stack))

		current->personality |= READ_IMPLIES_EXEC;



	setup_new_exec(bprm);



	set_binfmt(&elf_fdpic_format);



	current->mm->start_code = 0;