[PATCH] ocfs2: reduce ioctl stack usage

Arnd Bergmann
2023-04-17T21:00:45Z

From: Arnd Bergmann <arnd@arndb.de>

On 32-bit architectures with KASAN_STACK enabled, the total stack usage
of the ocfs2_ioctl function grows beyond the warning limit:

fs/ocfs2/ioctl.c: In function 'ocfs2_ioctl':
fs/ocfs2/ioctl.c:934:1: error: the frame size of 1448 bytes is larger than 1400 bytes [-Werror=frame-larger-than=]

Move each of the variables into a basic block, and mark ocfs2_info_handle()
as noinline_for_stack, in order to have the variable share stack slots.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
fs/ocfs2/ioctl.c | 37 ++++++++++++++++++++++++++-----------
1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
index 811a6ea374bb..b1550ba73f96 100644
--- a/fs/ocfs2/ioctl.c
+++ b/fs/ocfs2/ioctl.c
@@ -803,8 +803,8 @@ static int ocfs2_get_request_ptr(struct ocfs2_info *info, int idx,
* a better backward&forward compatibility, since a small piece of
* request will be less likely to be broken if disk layout get changed.
*/
-static int ocfs2_info_handle(struct inode *inode, struct ocfs2_info *info,
- int compat_flag)
+static noinline_for_stack int
+ocfs2_info_handle(struct inode *inode, struct ocfs2_info *info, int compat_flag)
{
int i, status = 0;
u64 req_addr;
@@ -840,27 +840,26 @@ static int ocfs2_info_handle(struct inode *inode, struct ocfs2_info *info,
long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
- int new_clusters;
- int status;
- struct ocfs2_space_resv sr;
- struct ocfs2_new_group_input input;
- struct reflink_arguments args;
- const char __user *old_path;
- const char __user *new_path;
- bool preserve;
- struct ocfs2_info info;
void __user *argp = (void __user *)arg;
+ int status;

switch (cmd) {
case OCFS2_IOC_RESVSP:
case OCFS2_IOC_RESVSP64:
case OCFS2_IOC_UNRESVSP:
case OCFS2_IOC_UNRESVSP64:
+ {
+ struct ocfs2_space_resv sr;
+
if (copy_from_user(&sr, (int __user *) arg, sizeof(sr)))
return -EFAULT;

return ocfs2_change_file_space(filp, cmd, &sr);
+ }
case OCFS2_IOC_GROUP_EXTEND:
+ {
+ int new_clusters;
+
if (!capable(CAP_SYS_RESOURCE))
return -EPERM;

@@ -873,8 +872,12 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
status = ocfs2_group_extend(inode, new_clusters);
mnt_drop_write_file(filp);
return status;
+ }
case OCFS2_IOC_GROUP_ADD:
case OCFS2_IOC_GROUP_ADD64:
+ {
+ struct ocfs2_new_group_input input;
+
if (!capable(CAP_SYS_RESOURCE))
return -EPERM;

@@ -887,7 +890,14 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
status = ocfs2_group_add(inode, &input);
mnt_drop_write_file(filp);
return status;
+ }
case OCFS2_IOC_REFLINK:
+ {
+ struct reflink_arguments args;
+ const char __user *old_path;
+ const char __user *new_path;
+ bool preserve;
+
if (copy_from_user(&args, argp, sizeof(args)))
return -EFAULT;
old_path = (const char __user *)(unsigned long)args.old_path;
@@ -895,11 +905,16 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
preserve = (args.preserve != 0);

return ocfs2_reflink_ioctl(inode, old_path, new_path, preserve);
+ }
case OCFS2_IOC_INFO:
+ {
+ struct ocfs2_info info;
+
if (copy_from_user(&info, argp, sizeof(struct ocfs2_info)))
return -EFAULT;

return ocfs2_info_handle(inode, &info, 0);
+ }
case FITRIM:
{
struct super_block *sb = inode->i_sb;
--
2.39.2