Messages in this thread Patch in this message | | | Subject | [FIX] Long-standing xattr sharing bug | From | Andreas Gruenbacher <> | Date | Sat, 05 Feb 2005 19:03:23 +0100 |
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When looking for identical xattr blocks to share, we were not comparing the name_index fields. This could lead to false sharing when two xattr blocks ended up with identical attribute names and values, and the only difference was in name_index. Specifically this could trigger with default acls. Because acls are cached, the bug was hidden until the next reload of the affected inode.
$ mkdir -m 700 a b $ setfacl -m u:bin:rwx a < acl of a goes in the mbcache
$ setfacl -dm u:bin:rwx b < acl of b differs only in name_index, so a's acl is reused
$ getfacl b < shows the result from the inode cache
< empty inode cache (remount, etc.)
$ getfacl b < shows an access acl instead of a default acl.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Index: linux-2.6.11-rc3/fs/ext2/xattr.c =================================================================== --- linux-2.6.11-rc3.orig/fs/ext2/xattr.c +++ linux-2.6.11-rc3/fs/ext2/xattr.c @@ -881,6 +881,7 @@ ext2_xattr_cmp(struct ext2_xattr_header if (IS_LAST_ENTRY(entry2)) return 1; if (entry1->e_hash != entry2->e_hash || + entry1->e_name_index != entry2->e_name_index || entry1->e_name_len != entry2->e_name_len || entry1->e_value_size != entry2->e_value_size || memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) Index: linux-2.6.11-rc3/fs/ext3/xattr.c =================================================================== --- linux-2.6.11-rc3.orig/fs/ext3/xattr.c +++ linux-2.6.11-rc3/fs/ext3/xattr.c @@ -1162,6 +1162,7 @@ ext3_xattr_cmp(struct ext3_xattr_header if (IS_LAST_ENTRY(entry2)) return 1; if (entry1->e_hash != entry2->e_hash || + entry1->e_name_index != entry2->e_name_index || entry1->e_name_len != entry2->e_name_len || entry1->e_value_size != entry2->e_value_size || memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
Regards, -- Andreas Gruenbacher <agruen@suse.de> SUSE Labs, SUSE LINUX GMBH
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