[PATCH AUTOSEL 4.14 1/2] init/Kconfig: fix LOCALVERSION_AUTO help text

[PATCH AUTOSEL 4.14 1/2] init/Kconfig: fix LOCALVERSION_AUTO help text

[Sasha Levin]

From: Rasmus Villemoes <linux@rasmusvillemoes.dk>

[ Upstream commit 0f9c608d4a1eb852d6769d2fc5906c71c02565ae ]

It was never guaranteed to be exactly eight, but since commit
548b8b5168c9 ("scripts/setlocalversion: make git describe output more
reliable"), it has been exactly 12.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 init/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/init/Kconfig b/init/Kconfig
index c87858c434cc..bc3c44f6b503 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -101,7 +101,7 @@ config LOCALVERSION_AUTO
 	  appended after any matching localversion* files, and after the value
 	  set in CONFIG_LOCALVERSION.
 
-	  (The actual string used here is the first eight characters produced
+	  (The actual string used here is the first 12 characters produced
 	  by running the command:
 
 	    $ git rev-parse --verify HEAD
-- 
2.39.0

[PATCH AUTOSEL 4.14 2/2] ext4: deal with legacy signed xattr name hash values

[Sasha Levin]

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit f3bbac32475b27f49be201f896d98d4009de1562 ]

We potentially have old hashes of the xattr names generated on systems
with signed 'char' types.  Now that everybody uses '-funsigned-char',
those hashes will no longer match.

This only happens if you use xattrs names that have the high bit set,
which probably doesn't happen in practice, but the xfstest generic/454
shows it.

Instead of adding a new "signed xattr hash filesystem" bit and having to
deal with all the possible combinations, just calculate the hash both
ways if the first one fails, and always generate new hashes with the
proper unsigned char version.

Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/oe-lkp/202212291509.704a11c9-oliver.sang@intel.com
Link: https://lore.kernel.org/all/CAHk-=whUNjwqZXa-MH9KMmc_CpQpoFKFjAB9ZKHuu=TbsouT4A@mail.gmail.com/
Exposed-by: 3bc753c06dd0 ("kbuild: treat char as always unsigned")
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Andreas Dilger <adilger@dilger.ca>
Cc: Theodore Ts'o <tytso@mit.edu>,
Cc: Jason Donenfeld <Jason@zx2c4.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ext4/xattr.c | 41 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 8a3f0e20c51e..2397fbbe259c 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -80,6 +80,8 @@ ext4_xattr_block_cache_find(struct inode *, struct ext4_xattr_header *,
 			    struct mb_cache_entry **);
 static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
 				    size_t value_count);
+static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value,
+				    size_t value_count);
 static void ext4_xattr_rehash(struct ext4_xattr_header *);
 
 static const struct xattr_handler * const ext4_xattr_handler_map[] = {
@@ -452,8 +454,21 @@ ext4_xattr_inode_verify_hashes(struct inode *ea_inode,
 		tmp_data = cpu_to_le32(hash);
 		e_hash = ext4_xattr_hash_entry(entry->e_name, entry->e_name_len,
 					       &tmp_data, 1);
-		if (e_hash != entry->e_hash)
-			return -EFSCORRUPTED;
+		/* All good? */
+		if (e_hash == entry->e_hash)
+			return 0;
+
+		/*
+		 * Not good. Maybe the entry hash was calculated
+		 * using the buggy signed char version?
+		 */
+		e_hash = ext4_xattr_hash_entry_signed(entry->e_name, entry->e_name_len,
+							&tmp_data, 1);
+		if (e_hash == entry->e_hash)
+			return 0;
+
+		/* Still no match - bad */
+		return -EFSCORRUPTED;
 	}
 	return 0;
 }
@@ -3107,6 +3122,28 @@ static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
 	return cpu_to_le32(hash);
 }
 
+/*
+ * ext4_xattr_hash_entry_signed()
+ *
+ * Compute the hash of an extended attribute incorrectly.
+ */
+static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value, size_t value_count)
+{
+	__u32 hash = 0;
+
+	while (name_len--) {
+		hash = (hash << NAME_HASH_SHIFT) ^
+		       (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
+		       (signed char)*name++;
+	}
+	while (value_count--) {
+		hash = (hash << VALUE_HASH_SHIFT) ^
+		       (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
+		       le32_to_cpu(*value++);
+	}
+	return cpu_to_le32(hash);
+}
+
 #undef NAME_HASH_SHIFT
 #undef VALUE_HASH_SHIFT
 
-- 
2.39.0