On Wed, Feb 05, 2025 at 09:20:07AM -0300, Thadeu Lima de Souza Cascardo wrote:
tpm_chip_start may issue IO that should not be done while the chip is suspended. In the particular case of I2C, it will issue the following warning:
The bug is legit but this description needs some rework:
"Checking TPM_CHIP_FLAG_SUSPENDED after the call to tpm_chip_find_get_ops() can lead to a spurious tpm_chip_start_call()":
[35985.503771] i2c i2c-1: Transfer while suspended [35985.503796] WARNING: CPU: 0 PID: 74 at drivers/i2c/i2c-core.h:56 __i2c_transfer+0xbe/0x810 [35985.503802] Modules linked in: [35985.503808] CPU: 0 UID: 0 PID: 74 Comm: hwrng Tainted: G W 6.13.0-next-20250203-00005-gfa0cb5642941 #19 9c3d7f78192f2d38e32010ac9c90fdc71109ef6f [35985.503814] Tainted: [W]=WARN [35985.503817] Hardware name: Google Morphius/Morphius, BIOS Google_Morphius.13434.858.0 10/26/2023 [35985.503819] RIP: 0010:__i2c_transfer+0xbe/0x810 [35985.503825] Code: 30 01 00 00 4c 89 f7 e8 40 fe d8 ff 48 8b 93 80 01 00 00 48 85 d2 75 03 49 8b 16 48 c7 c7 0a fb 7c a7 48 89 c6 e8 32 ad b0 fe <0f> 0b b8 94 ff ff ff e9 33 04 00 00 be 02 00 00 00 83 fd 02 0f 5 [35985.503828] RSP: 0018:ffffa106c0333d30 EFLAGS: 00010246 [35985.503833] RAX: 074ba64aa20f7000 RBX: ffff8aa4c1167120 RCX: 0000000000000000 [35985.503836] RDX: 0000000000000000 RSI: ffffffffa77ab0e4 RDI: 0000000000000001 [35985.503838] RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000 [35985.503841] R10: 0000000000000004 R11: 00000001000313d5 R12: ffff8aa4c10f1820 [35985.503843] R13: ffff8aa4c0e243c0 R14: ffff8aa4c1167250 R15: ffff8aa4c1167120 [35985.503846] FS: 0000000000000000(0000) GS:ffff8aa4eae00000(0000) knlGS:0000000000000000 [35985.503849] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [35985.503852] CR2: 00007fab0aaf1000 CR3: 0000000105328000 CR4: 00000000003506f0 [35985.503855] Call Trace: [35985.503859] <TASK> [35985.503863] ? __warn+0xd4/0x260 [35985.503868] ? __i2c_transfer+0xbe/0x810 [35985.503874] ? report_bug+0xf3/0x210 [35985.503882] ? handle_bug+0x63/0xb0 [35985.503887] ? exc_invalid_op+0x16/0x50 [35985.503892] ? asm_exc_invalid_op+0x16/0x20 [35985.503904] ? __i2c_transfer+0xbe/0x810 [35985.503913] tpm_cr50_i2c_transfer_message+0x24/0xf0 [35985.503920] tpm_cr50_i2c_read+0x8e/0x120 [35985.503928] tpm_cr50_request_locality+0x75/0x170 [35985.503935] tpm_chip_start+0x116/0x160
Only put this snippe to the commit message.
Test for the suspended flag inside tpm_try_get_ops while holding the chip tpm_mutex before calling tpm_chip_start. That will also prevent tpm_get_random from doing IO while the TPM is suspended.
Remove and:
"Don't move forward with tpm_chip_start() inside tpm_chip_find_get(), unless TPM_CHIP_FLAG_SUSPENDED is set. Return NULl in the failure case."
Fixes: 9265fed6db60 ("tpm: Lock TPM chip in tpm_pm_suspend() first") Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@igalia.com Cc: stable@vger.kernel.org Cc: Jerry Snitselaar jsnitsel@redhat.com Cc: Mike Seo mikeseohyungjin@gmail.com Cc: Jarkko Sakkinen jarkko@kernel.org
drivers/char/tpm/tpm-chip.c | 5 +++++ drivers/char/tpm/tpm-interface.c | 8 +------- 2 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 7df7abaf3e526bf7e85ac9dfbaa1087a51d2ab7e..6db864696a583bf59c534ec8714900a6be7b5156 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -168,6 +168,11 @@ int tpm_try_get_ops(struct tpm_chip *chip) goto out_ops; mutex_lock(&chip->tpm_mutex);
- /* tmp_chip_start may issue IO that is denied while suspended */
- if (chip->flags & TPM_CHIP_FLAG_SUSPENDED)
goto out_lock;- rc = tpm_chip_start(chip); if (rc) goto out_lock;
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index b1daa0d7b341b1a4c71a200115f0d29d2e87512d..e6d786ce4e36970428b75d288a066e832c5b2af1 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -441,22 +441,16 @@ int tpm_get_random(struct tpm_chip *chip, u8 *out, size_t max) if (!out || max > TPM_MAX_RNG_DATA) return -EINVAL;
- /* NULL will be returned if chip is suspended */
spurious diff, remove
chip = tpm_find_get_ops(chip); if (!chip) return -ENODEV;
- /* Give back zero bytes, as TPM chip has not yet fully resumed: */
- if (chip->flags & TPM_CHIP_FLAG_SUSPENDED) {
rc = 0;goto out;- }
- if (chip->flags & TPM_CHIP_FLAG_TPM2) rc = tpm2_get_random(chip, out, max); else rc = tpm1_get_random(chip, out, max);
-out: tpm_put_ops(chip); return rc; }
base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b change-id: 20250205-tpm-suspend-b22f745f3124
Best regards,
Thadeu Lima de Souza Cascardo cascardo@igalia.com
BR, Jarkko