Commit 864778b1 authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
Browse files

mm, aout: handle vm_brk failures 



vm_brk is allowed to fail but load_aout_binary simply ignores the error
and happily continues.  I haven't noticed any problem from that in real
life but later patches will make the failure more likely because vm_brk
will become killable (resp.  mmap_sem for write waiting will become
killable) so we should be more careful now.

The error handling should be quite straightforward because there are
calls to vm_mmap which check the error properly already.  The only
notable exception is set_brk which is called after beyond_if label.  But
nothing indicates that we cannot move it above set_binfmt as the two do
not depend on each other and fail before we do set_binfmt and alter
reference counting.

Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ae798783

arch/x86/ia32/ia32_aout.c

+15 −7
Original line number Diff line number Diff line
@@ -116,13 +116,13 @@ static struct linux_binfmt aout_format = { 
	.min_coredump	= PAGE_SIZE

};



static void set_brk(unsigned long start, unsigned long end)

static unsigned long set_brk(unsigned long start, unsigned long end)

{

	start = PAGE_ALIGN(start);

	end = PAGE_ALIGN(end);

	if (end <= start)

		return;

	vm_brk(start, end - start);

		return start;

	return vm_brk(start, end - start);

}



#ifdef CONFIG_COREDUMP
@@ -349,7 +349,10 @@ static int load_aout_binary(struct linux_binprm *bprm) 
#endif



		if (!bprm->file->f_op->mmap || (fd_offset & ~PAGE_MASK) != 0) {

			vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);

			error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);

			if (IS_ERR_VALUE(error))

				return error;



			read_code(bprm->file, N_TXTADDR(ex), fd_offset,

					ex.a_text+ex.a_data);

			goto beyond_if;
@@ -372,10 +375,13 @@ static int load_aout_binary(struct linux_binprm *bprm) 
		if (error != N_DATADDR(ex))

			return error;

	}



beyond_if:

	set_binfmt(&aout_format);

	error = set_brk(current->mm->start_brk, current->mm->brk);

	if (IS_ERR_VALUE(error))

		return error;



	set_brk(current->mm->start_brk, current->mm->brk);

	set_binfmt(&aout_format);



	current->mm->start_stack =

		(unsigned long)create_aout_tables((char __user *)bprm->p, bprm);
@@ -434,7 +440,9 @@ static int load_aout_library(struct file *file) 
			error_time = jiffies;

		}

#endif

		vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);

		retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);

		if (IS_ERR_VALUE(retval))

			goto out;



		read_code(file, start_addr, N_TXTOFF(ex),

			  ex.a_text + ex.a_data);

fs/binfmt_aout.c

+8 −3
Original line number Diff line number Diff line
@@ -297,7 +297,10 @@ static int load_aout_binary(struct linux_binprm * bprm) 
		}



		if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {

			vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);

			error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);

			if (IS_ERR_VALUE(error))

				return error;



			read_code(bprm->file, N_TXTADDR(ex), fd_offset,

				  ex.a_text + ex.a_data);

			goto beyond_if;
@@ -378,7 +381,9 @@ static int load_aout_library(struct file *file) 
			       "N_TXTOFF is not page aligned. Please convert library: %pD\n",

			       file);

		}

		vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);

		retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);

		if (IS_ERR_VALUE(retval))

			goto out;



		read_code(file, start_addr, N_TXTOFF(ex),

			  ex.a_text + ex.a_data);

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