On Wed, 2020-06-03 at 17:08 +0200, Roberto Sassu wrote:
> This patch prevents the following oops:
>
> [ 10.771813] BUG: kernel NULL pointer dereference, address: 0000000000000
> [...]
> [ 10.779790] RIP: 0010:ima_match_policy+0xf7/0xb80
> [...]
> [ 10.798576] Call Trace:
> [ 10.798993] ? ima_lsm_policy_change+0x2b0/0x2b0
> [ 10.799753] ? inode_init_owner+0x1a0/0x1a0
> [ 10.800484] ? _raw_spin_lock+0x7a/0xd0
> [ 10.801592] ima_must_appraise.part.0+0xb6/0xf0
> [ 10.802313] ? ima_fix_xattr.isra.0+0xd0/0xd0
> [ 10.803167] ima_must_appraise+0x4f/0x70
> [ 10.804004] ima_post_path_mknod+0x2e/0x80
> [ 10.804800] do_mknodat+0x396/0x3c0
>
> It occurs when there is a failure during IMA initialization, and
> ima_init_policy() is not called. IMA hooks still call ima_match_policy()
> but ima_rules is NULL. This patch prevents the crash by directly assigning
> the ima_default_policy pointer to ima_rules when ima_rules is defined. This
> wouldn't alter the existing behavior, as ima_rules is always set at the end
> of ima_init_policy().
>
> Cc: stable@xxxxxxxxxxxxxxx # 3.7.x
> Fixes: 07f6a79415d7d ("ima: add appraise action keywords and default rules")
> Reported-by: Takashi Iwai <tiwai@xxxxxxx>
> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Thanks, Roberto!
