[PATCH v2] exfat: fix name_hash computation on big endian systems

[PATCH v2] exfat: fix name_hash computation on big endian systems

[Ilya Ponetaev]

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Hello!

I tested current kernel 5.8 on MIPS BE CPU, and found that name_hash 
field of directory entry is computed incorrectly due to lack of 
endianess conversion.

It leads to errors in directories listing and opening files:

~# ls /mnt/sda1/
ls: /mnt/sda1/System Volume Information: No such file or directory
ls: /mnt/sda1/node.exe: No such file or directory
ls: /mnt/sda1/node_etw_provider.man: No such file or directory
ls: /mnt/sda1/nodevars.bat: No such file or directory
ls: /mnt/sda1/npm: No such file or directory
ls: /mnt/sda1/npm.cmd: No such file or directory
ls: /mnt/sda1/npx: No such file or directory
ls: /mnt/sda1/npx.cmd: No such file or directory


v2:
  - fixed sparse errors

sparse warnings: (new ones prefixed by >>)

 >> fs/exfat/nls.c:522:27: sparse: sparse: incorrect type in assignment 
(different base types) @@     expected unsigned short @@     got 
restricted __le16 [usertype] @@
 >> fs/exfat/nls.c:522:27: sparse:     expected unsigned short
 >> fs/exfat/nls.c:522:27: sparse:     got restricted __le16 [usertype]
    fs/exfat/nls.c:614:32: sparse: sparse: incorrect type in assignment 
(different base types) @@     expected unsigned short @@     got 
restricted __le16 [usertype] @@
    fs/exfat/nls.c:614:32: sparse:     expected unsigned short
    fs/exfat/nls.c:614:32: sparse:     got restricted __le16 [usertype]



Sincerely yours,
Ilya Ponetayev

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From f6d2c94c57189c162ccb531d10909d6d7f77c058 Mon Sep 17 00:00:00 2001
From: Ilya Ponetayev <i.ponetaev@ndmsystems.com>
Date: Tue, 7 Jul 2020 23:02:30 +0300
Subject: [PATCH] exfat: fix name_hash computation on big endian systems

On-disk format for name_hash field is LE, so it must be explicitly transformed
on BE system for proper result.

Signed-off-by: Chen Minqiang <ptpt52@gmail.com>
Signed-off-by: Ilya Ponetayev <i.ponetaev@ndmsystems.com>
---
 nls.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/nls.c b/nls.c
index d48060a..1a70138 100644
--- a/nls.c
+++ b/nls.c
@@ -494,7 +494,7 @@ static int exfat_utf8_to_utf16(struct super_block *sb,
 		struct exfat_uni_name *p_uniname, int *p_lossy)
 {
 	int i, unilen, lossy = NLS_NAME_NO_LOSSY;
-	unsigned short upname[MAX_NAME_LENGTH + 1];
+	__le16 upname[MAX_NAME_LENGTH + 1];
 	unsigned short *uniname = p_uniname->name;
 
 	WARN_ON(!len);
@@ -518,7 +518,7 @@ static int exfat_utf8_to_utf16(struct super_block *sb,
 		    exfat_wstrchr(bad_uni_chars, *uniname))
 			lossy |= NLS_NAME_LOSSY;
 
-		upname[i] = exfat_toupper(sb, *uniname);
+		upname[i] = cpu_to_le16(exfat_toupper(sb, *uniname));
 		uniname++;
 	}
 
@@ -596,7 +596,7 @@ static int exfat_nls_to_ucs2(struct super_block *sb,
 		struct exfat_uni_name *p_uniname, int *p_lossy)
 {
 	int i = 0, unilen = 0, lossy = NLS_NAME_NO_LOSSY;
-	unsigned short upname[MAX_NAME_LENGTH + 1];
+	__le16 upname[MAX_NAME_LENGTH + 1];
 	unsigned short *uniname = p_uniname->name;
 	struct nls_table *nls = EXFAT_SB(sb)->nls_io;
 
@@ -610,7 +610,7 @@ static int exfat_nls_to_ucs2(struct super_block *sb,
 		    exfat_wstrchr(bad_uni_chars, *uniname))
 			lossy |= NLS_NAME_LOSSY;
 
-		upname[unilen] = exfat_toupper(sb, *uniname);
+		upname[unilen] = cpu_to_le16(exfat_toupper(sb, *uniname));
 		uniname++;
 		unilen++;
 	}