ext4: limit xattr size to INT_MAX
authorEric Biggers <ebiggers@google.com>
Thu, 29 Mar 2018 18:31:42 +0000 (14:31 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 24 Apr 2018 07:36:30 +0000 (09:36 +0200)
commita57eb14b740e6175aff8b8941bec628403992dfa
tree7c64b6831765a8022a8513e7a388091fafa0edd5
parent5058b70d2118ee0304a2f3124946c4089b06abde
ext4: limit xattr size to INT_MAX

commit ce3fd194fcc6fbdc00ce095a852f22df97baa401 upstream.

ext4 isn't validating the sizes of xattrs where the value of the xattr
is stored in an external inode.  This is problematic because
->e_value_size is a u32, but ext4_xattr_get() returns an int.  A very
large size is misinterpreted as an error code, which ext4_get_acl()
translates into a bogus ERR_PTR() for which IS_ERR() returns false,
causing a crash.

Fix this by validating that all xattrs are <= INT_MAX bytes.

This issue has been assigned CVE-2018-1095.

https://bugzilla.kernel.org/show_bug.cgi?id=199185
https://bugzilla.redhat.com/show_bug.cgi?id=1560793

Reported-by: Wen Xu <wen.xu@gatech.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Fixes: e50e5129f384 ("ext4: xattr-in-inode support")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/ext4/xattr.c