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 15c02e15d3fd..b072772eb3a7 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -105,7 +105,7 @@ 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

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=Tbsou... 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 0772941bbe92..c26a349af40b 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -81,6 +81,8 @@ 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[] = { @@ -468,8 +470,21 @@ 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; } @@ -3121,6 +3136,28 @@ 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