From 1a70f0b71826fb764e8490dda55bb1b853e0d1de Mon Sep 17 00:00:00 2001 From: Jiangshan Yi Date: Tue, 1 Sep 2026 17:30:49 +0300 Subject: [PATCH 1/4] tpm: Fix heap buffer overflow in tpm_transmit_cmd() struct tpm_buf now uses an embedded flexible array for data, which is 6 bytes shorter than TPM_BUFSIZE due to the struct header. But tpm_transmit_cmd() still passes PAGE_SIZE to tpm_transmit(), and after clamping to TPM_BUFSIZE in tpm_try_transmit(), chip->ops->recv() can write past the end of data[] by 6 bytes. Pass buf->capacity to tpm_transmit() instead. Fixes: 3d9e043dab0a ("tpm-buf: Memory-safe allocations") Signed-off-by: Jiangshan Yi Link: https://lore.kernel.org/r/20260901062850.379870-1-yijiangshan@kylinos.cn Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm-interface.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index f745a098908b..1ccdbde98b69 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -268,7 +268,7 @@ ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf, int err; ssize_t len; - len = tpm_transmit(chip, buf->data, PAGE_SIZE); + len = tpm_transmit(chip, buf->data, buf->capacity); if (len < 0) return len; From 1e2f9a611b334ce6ed1dc4a9e1587c7a11d2be30 Mon Sep 17 00:00:00 2001 From: Jiangshan Yi Date: Wed, 2 Sep 2026 15:48:39 +0800 Subject: [PATCH 2/4] tpm: Fix auth session leak in tpm2_get_random() error path When tpm_buf_fill_hmac_session() fails in tpm2_get_random(), the error path returns without calling tpm2_end_auth_session(), leaking the auth session. All other error paths in the function handle this correctly. Fixes: 3d9e043dab0a ("tpm-buf: Memory-safe allocations") Cc: stable@vger.kernel.orga # v6.12+ Signed-off-by: Jiangshan Yi Link: https://lore.kernel.org/r/20260902074839.417419-1-yijiangshan@kylinos.cn Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm2-cmd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 48cec39995fe..96e0e06bbbf0 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -281,8 +281,10 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) } tpm_buf_append_u16(buf, num_bytes); err = tpm_buf_fill_hmac_session(chip, buf); - if (err) + if (err) { + tpm2_end_auth_session(chip); return err; + } err = tpm_transmit_cmd(chip, buf, offsetof(struct tpm2_get_random_out, From 9b522400bf5c082feb9a0037a053ea822a2c7e4d Mon Sep 17 00:00:00 2001 From: Jiangshan Yi Date: Thu, 3 Sep 2026 11:58:37 +0800 Subject: [PATCH 3/4] tpm: fix off-by-four bounds check in tpm2_get_random() When the response carries the TPM2_ST_SESSIONS tag, tpm2_get_random() skips the 4-byte parameter size field before locating the random data, but the bounds check still validates the response length against TPM_HEADER_SIZE. A truncated response can pass the check and make memcpy() read up to 4 bytes past the response end, so stale buffer contents end up in the caller's random bytes. Fix this by checking the response length against 'offset', which already includes the skipped parameter size field. Cc: stable@vger.kernel.org # v6.12+ Fixes: 1b6d7f9eb150 ("tpm: add session encryption protection to tpm2_get_random()") Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260902074839.417419-1-yijiangshan%40kylinos.cn Signed-off-by: Jiangshan Yi Reviewed-by: Jarkko Sakkinen Link: https://lore.kernel.org/r/20260903035837.219284-1-yijiangshan@kylinos.cn Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm2-cmd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 96e0e06bbbf0..ae22295df798 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -307,7 +307,7 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) out = (struct tpm2_get_random_out *)&buf->data[offset]; recd = min_t(u32, be16_to_cpu(out->size), num_bytes); if (tpm_buf_length(buf) < - TPM_HEADER_SIZE + + offset + offsetof(struct tpm2_get_random_out, buffer) + recd) { tpm2_end_auth_session(chip); From 015fb29a748342a186f37b602ac70017098c8251 Mon Sep 17 00:00:00 2001 From: Surendran Kanagaraj Date: Fri, 18 Sep 2026 00:07:31 +0000 Subject: [PATCH 4/4] tpm: Disable TPM on null key name mismatch The null key name check exists to protect against TPM reset attacks, so a mismatch should stop the device from serving further requests. Currently it does not disable the chip when it finds a mismatch. The mismatch is logged: tpm tpm0: null key integrity check failed but the chip keeps serving commands: / # tpm2_getcap -c properties-fixed TPM_PT_FAMILY_INDICATOR: as UINT32: 0x08322e3000 as string: "2.0" ... tpm2_load_null() where the null key name check is run sets the chip as disabled only if the rc is non zero. When the mismatch is seen, rc is zero at that point and it returns success. The other issue is that the caller expects the null key handle to be populated when the function returns 0 which it does here without writing the handle and proceeds assuming the null key handle is valid. During the test, I noticed that tpm2_start_auth_session() uses the uninitialized stack value as the key handle since tpm2_load_null() returns 0 despite the integrity failure and proceeds with TPM2_CC_START_AUTH_SESS with this value as salt key handle. Set rc to -ENODEV on the mismatch. The error path then disables the chip and returns the correct code to the caller. Tested in QEMU with swtpm and CONFIG_TCG_TPM2_HMAC=y by making TPM2_CC_CONTEXT_LOAD fail with TPM2_RC_INTEGRITY and changing the name of the re-created null key. The chip is now disabled on the mismatch. Fixes: cc7d8594342a ("tpm: Rollback tpm2_load_null()") Fixes: 423893fcbe7e ("tpm: Disable TPM on tpm2_create_primary() failure") Cc: stable@vger.kernel.org # v6.12+ Assisted-by: LLM Signed-off-by: Surendran Kanagaraj Link: https://lore.kernel.org/r/20260918000731.48657-1-surenkj@amazon.com Reviewed-by: Gunnar Kudrjavets Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm2-sessions.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index cf8f1fd6790b..ca1e2bf424e1 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -975,6 +975,7 @@ static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key) /* Deduce from the name change TPM interference: */ dev_err(&chip->dev, "null key integrity check failed\n"); tpm2_flush_context(chip, tmp_null_key); + rc = -ENODEV; err: if (rc) {