On Tue, 2026-01-27 at 03:05 +0000, Dmitry Safonov via B4 Relay wrote:
> From: Dmitry Safonov <[email protected]>
>
> ima_init_crypto() skips initializing ima_algo_array[i] if the alogorithm
Algorithm.
> from ima_tpm_chip->allocated_banks[i].crypto_id is not supported.
> It seems avoid adding the unsupported algorithm to ima_algo_array will
> break all the logic that relies on indexing by NR_BANKS(ima_tpm_chip).
>
> Grepping HASH_ALGO__LAST in security/integrity/ima/ shows that is
> the check other logic relies on, so make
> create_securityfs_measurement_lists() ignore unknown algorithms.
>
> On 6.12.40 I observe the following read out-of-bounds in hash_algo_name:
>
> > ==================================================================
> > BUG: KASAN: global-out-of-bounds in
> > create_securityfs_measurement_lists+0x396/0x440
> > Read of size 8 at addr ffffffff83e18138 by task swapper/0/1
> >
> > CPU: 4 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.40 #3
> > Call Trace:
> > <TASK>
> > dump_stack_lvl+0x61/0x90
> > print_report+0xc4/0x580
> > ? kasan_addr_to_slab+0x26/0x80
> > ? create_securityfs_measurement_lists+0x396/0x440
> > kasan_report+0xc2/0x100
> > ? create_securityfs_measurement_lists+0x396/0x440
> > create_securityfs_measurement_lists+0x396/0x440
> > ima_fs_init+0xa3/0x300
> > ima_init+0x7d/0xd0
> > init_ima+0x28/0x100
> > do_one_initcall+0xa6/0x3e0
> > kernel_init_freeable+0x455/0x740
> > kernel_init+0x24/0x1d0
> > ret_from_fork+0x38/0x80
> > ret_from_fork_asm+0x11/0x20
> > </TASK>
> >
> > The buggy address belongs to the variable:
> > hash_algo_name+0xb8/0x420
> >
> > The buggy address belongs to the physical page:
> > page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x107ce18
> > flags: 0x8000000000002000(reserved|zone=2)
> > raw: 8000000000002000 ffffea0041f38608 ffffea0041f38608 0000000000000000
> > raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
> > page dumped because: kasan: bad access detected
> >
> > Memory state around the buggy address:
> > ffffffff83e18000: 00 01 f9 f9 f9 f9 f9 f9 00 01 f9 f9 f9 f9 f9 f9
> > ffffffff83e18080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > > ffffffff83e18100: 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 00 05 f9 f9
> > ^
> > ffffffff83e18180: f9 f9 f9 f9 00 00 00 00 00 00 00 04 f9 f9 f9 f9
> > ffffffff83e18200: 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9 f9 f9 f9
> > ==================================================================
>
> Seems like the TPM chip supports sha3_256, which isn't yet in
> tpm_algorithms:
> > tpm tpm0: TPM with unsupported bank algorithm 0x0027
>
> Fixes: 9fa8e7625008 ("ima: add crypto agility support for template-hash
> algorithm")
> Signed-off-by: Dmitry Safonov <[email protected]>
> Cc: Enrico Bravi <[email protected]>
> Cc: Silvia Sisinni <[email protected]>
> Cc: Roberto Sassu <[email protected]>
> Cc: Mimi Zohar <[email protected]>
> ---
> security/integrity/ima/ima_fs.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
> index 012a58959ff0..e9283229acea 100644
> --- a/security/integrity/ima/ima_fs.c
> +++ b/security/integrity/ima/ima_fs.c
> @@ -404,6 +404,9 @@ static int __init
> create_securityfs_measurement_lists(void)
> char file_name[NAME_MAX + 1];
> struct dentry *dentry;
>
> + if (algo == HASH_ALGO__LAST)
> + continue;
> +
> sprintf(file_name, "ascii_runtime_measurements_%s",
> hash_algo_name[algo]);
Thanks, but I think we can also print the unsupported digests, since
they are there. Since we don't have the algorithm name, we can make
ours like tpm_<algo hex>.
Once this is fixed, you can try to make SHA3_256 supported. Add the
TPM_ALG_SHA3_256 definition in tpm.h and the mapping in tpm2-cmd.c
(array tpm2_hash_map).
Thanks
Roberto
> dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP,
>
> ---
> base-commit: 63804fed149a6750ffd28610c5c1c98cce6bd377
> change-id: 20260127-ima-oob-9fa83a634d7b
>
> Best regards,
