exfat: Avoid allocating upcase table using kcalloc()

The table for Unicode upcase conversion requires an order-5 allocation,
which may fail on a highly-fragmented system:

 pool-udisksd: page allocation failure: order:5,
 mode:0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), nodemask=(null),
 cpuset=/,mems_allowed=0
 CPU: 4 PID: 3756880 Comm: pool-udisksd Tainted: G U
 5.8.10-200.fc32.x86_64 #1
 Hardware name: Dell Inc. XPS 13 9360/0PVG6D, BIOS 2.13.0 11/14/2019
 Call Trace:
  dump_stack+0x6b/0x88
  warn_alloc.cold+0x75/0xd9
  ? _cond_resched+0x16/0x40
  ? __alloc_pages_direct_compact+0x144/0x150
  __alloc_pages_slowpath.constprop.0+0xcfa/0xd30
  ? __schedule+0x28a/0x840
  ? __wait_on_bit_lock+0x92/0xa0
  __alloc_pages_nodemask+0x2df/0x320
  kmalloc_order+0x1b/0x80
  kmalloc_order_trace+0x1d/0xa0
  exfat_create_upcase_table+0x115/0x390 [exfat]
  exfat_fill_super+0x3ef/0x7f0 [exfat]
  ? sget_fc+0x1d0/0x240
  ? exfat_init_fs_context+0x120/0x120 [exfat]
  get_tree_bdev+0x15c/0x250
  vfs_get_tree+0x25/0xb0
  do_mount+0x7c3/0xaf0
  ? copy_mount_options+0xab/0x180
  __x64_sys_mount+0x8e/0xd0
  do_syscall_64+0x4d/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Make the driver use kvcalloc() to eliminate the issue.

Fixes: 370e812b ("exfat: add nls operations")
Cc: stable@vger.kernel.org #v5.7+
Signed-off-by: Artem Labazov <123321artyom@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>

fs/exfat/nls.c

@@ -659,7 +659,7 @@ static int exfat_load_upcase_table(struct super_block *sb,
 	unsigned char skip = false;
 	unsigned short *upcase_table;
 
-	upcase_table = kcalloc(UTBL_COUNT, sizeof(unsigned short), GFP_KERNEL);
+	upcase_table = kvcalloc(UTBL_COUNT, sizeof(unsigned short), GFP_KERNEL);
 	if (!upcase_table)
 		return -ENOMEM;
 
@@ -715,7 +715,7 @@ static int exfat_load_default_upcase_table(struct super_block *sb)
 	unsigned short uni = 0, *upcase_table;
 	unsigned int index = 0;
 
-	upcase_table = kcalloc(UTBL_COUNT, sizeof(unsigned short), GFP_KERNEL);
+	upcase_table = kvcalloc(UTBL_COUNT, sizeof(unsigned short), GFP_KERNEL);
 	if (!upcase_table)
 		return -ENOMEM;
 
@@ -803,5 +803,5 @@ int exfat_create_upcase_table(struct super_block *sb)
 
 void exfat_free_upcase_table(struct exfat_sb_info *sbi)
 {
-	kfree(sbi->vol_utbl);
+	kvfree(sbi->vol_utbl);
 }