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| author | Kees Cook <keescook@chromium.org> | 2018-08-03 12:52:58 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2018-08-04 07:53:46 -0700 |
| commit | 961b33c244e5ba1543ae26270a1ba29f29c2db83 (patch) | |
| tree | b2e0bdb72b4e43774aa1264c9bf9f3df1e8cb2d8 /fs/jfs/jfs_incore.h | |
| parent | 7daf201d7fe8334e2d2364d4e8ed3394ec9af819 (diff) | |
| download | talos-obmc-linux-961b33c244e5ba1543ae26270a1ba29f29c2db83.tar.gz talos-obmc-linux-961b33c244e5ba1543ae26270a1ba29f29c2db83.zip | |
jfs: Fix usercopy whitelist for inline inode data
Bart Massey reported what turned out to be a usercopy whitelist false
positive in JFS when symlink contents exceeded 128 bytes. The inline
inode data (i_inline) is actually designed to overflow into the "extended
area" following it (i_inline_ea) when needed. So the whitelist needed to
be expanded to include both i_inline and i_inline_ea (the whole size
of which is calculated internally using IDATASIZE, 256, instead of
sizeof(i_inline), 128).
$ cd /mnt/jfs
$ touch $(perl -e 'print "B" x 250')
$ ln -s B* b
$ ls -l >/dev/null
[ 249.436410] Bad or missing usercopy whitelist? Kernel memory exposure attempt detected from SLUB object 'jfs_ip' (offset 616, size 250)!
Reported-by: Bart Massey <bart.massey@gmail.com>
Fixes: 8d2704d382a9 ("jfs: Define usercopy region in jfs_ip slab cache")
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: jfs-discussion@lists.sourceforge.net
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'fs/jfs/jfs_incore.h')
| -rw-r--r-- | fs/jfs/jfs_incore.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/jfs/jfs_incore.h b/fs/jfs/jfs_incore.h index 1f26d1910409..9940a1e04cbf 100644 --- a/fs/jfs/jfs_incore.h +++ b/fs/jfs/jfs_incore.h @@ -87,6 +87,7 @@ struct jfs_inode_info { struct { unchar _unused[16]; /* 16: */ dxd_t _dxd; /* 16: */ + /* _inline may overflow into _inline_ea when needed */ unchar _inline[128]; /* 128: inline symlink */ /* _inline_ea may overlay the last part of * file._xtroot if maxentry = XTROOTINITSLOT |
