fs: use rlimit helpers

Make sure compiler won't do weird things with limits.  E.g.  fetching them
twice may return 2 different values after writable limits are implemented.

I.e.  either use rlimit helpers added in commit 3e10e716abf3 ("resource:
add helpers for fetching rlimits") or ACCESS_ONCE if not applicable.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/attr.c

@@ -81,7 +81,7 @@ int inode_newsize_ok(const struct inode *inode, loff_t offset)
 	if (inode->i_size < offset) {
 		unsigned long limit;
 
-		limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+		limit = rlimit(RLIMIT_FSIZE);
 		if (limit != RLIM_INFINITY && offset > limit)
 			goto out_sig;
 		if (offset > inode->i_sb->s_maxbytes)

fs/binfmt_aout.c

@@ -247,7 +247,7 @@ static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 	 * size limits imposed on them by creating programs with large
 	 * arrays in the data or bss.
 	 */
-	rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
+	rlim = rlimit(RLIMIT_DATA);
 	if (rlim >= RLIM_INFINITY)
 		rlim = ~0;
 	if (ex.a_data + ex.a_bss > rlim)

fs/binfmt_flat.c

@@ -501,7 +501,7 @@ static int load_flat_file(struct linux_binprm * bprm,
 	 * size limits imposed on them by creating programs with large
 	 * arrays in the data or bss.
 	 */
-	rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
+	rlim = rlimit(RLIMIT_DATA);
 	if (rlim >= RLIM_INFINITY)
 		rlim = ~0;
 	if (data_len + bss_len > rlim) {

fs/exec.c

@@ -195,7 +195,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 		 *    to work from.
 		 */
 		rlim = current->signal->rlim;
-		if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
+		if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
 			put_page(page);
 			return NULL;
 		}
@@ -579,7 +579,7 @@ int setup_arg_pages(struct linux_binprm *bprm,
 
 #ifdef CONFIG_STACK_GROWSUP
 	/* Limit stack size to 1GB */
-	stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
+	stack_base = rlimit_max(RLIMIT_STACK);
 	if (stack_base > (1 << 30))
 		stack_base = 1 << 30;
 
@@ -1535,7 +1535,7 @@ static int format_corename(char *corename, long signr)
 			/* core limit size */
 			case 'c':
 				rc = snprintf(out_ptr, out_end - out_ptr,
-					      "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
+					      "%lu", rlimit(RLIMIT_CORE));
 				if (rc > out_end - out_ptr)
 					goto out;
 				out_ptr += rc;
@@ -1800,7 +1800,7 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
 	struct coredump_params cprm = {
 		.signr = signr,
 		.regs = regs,
-		.limit = current->signal->rlim[RLIMIT_CORE].rlim_cur,
+		.limit = rlimit(RLIMIT_CORE),
 	};
 
 	audit_core_dumps(signr);

fs/fcntl.c

@@ -344,7 +344,7 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 	switch (cmd) {
 	case F_DUPFD:
 	case F_DUPFD_CLOEXEC:
-		if (arg >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
+		if (arg >= rlimit(RLIMIT_NOFILE))
 			break;
 		err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);
 		if (err >= 0) {

fs/file.c

@@ -257,7 +257,7 @@ int expand_files(struct files_struct *files, int nr)
 	 * N.B. For clone tasks sharing a files structure, this test
 	 * will limit the total number of files that can be opened.
 	 */
-	if (nr >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
+	if (nr >= rlimit(RLIMIT_NOFILE))
 		return -EMFILE;
 
 	/* Do we need to expand? */

fs/proc/array.c

@@ -273,7 +273,7 @@ static inline void task_sig(struct seq_file *m, struct task_struct *p)
 		rcu_read_lock();  /* FIXME: is this correct? */
 		qsize = atomic_read(&__task_cred(p)->user->sigpending);
 		rcu_read_unlock();
-		qlim = p->signal->rlim[RLIMIT_SIGPENDING].rlim_cur;
+		qlim = task_rlimit(p, RLIMIT_SIGPENDING);
 		unlock_task_sighand(p, &flags);
 	}
 
@@ -420,7 +420,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 		cutime = sig->cutime;
 		cstime = sig->cstime;
 		cgtime = sig->cgtime;
-		rsslim = sig->rlim[RLIMIT_RSS].rlim_cur;
+		rsslim = ACCESS_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
 
 		/* add up live thread stats at the group level */
 		if (whole) {

fs/select.c

@@ -821,7 +821,7 @@ int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
  	struct poll_list *walk = head;
  	unsigned long todo = nfds;
 
-	if (nfds > current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
+	if (nfds > rlimit(RLIMIT_NOFILE))
 		return -EINVAL;
 
 	len = min_t(unsigned int, nfds, N_STACK_PPS);