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* FAILED: patch "[PATCH] tpm: fix off-by-four bounds check in tpm2_get_random()" failed to apply to 7.2-stable tree
@ 2026-10-03 13:20 gregkh
  2026-10-04  1:39 ` [PATCH 7.2.y 1/8] tpm: Initial step to reorganize TPM public headers Sasha Levin
  2026-10-05  7:54 ` [PATCH 7.2.y] " Jarkko Sakkinen
  0 siblings, 2 replies; 11+ messages in thread
From: gregkh @ 2026-10-03 13:20 UTC (permalink / raw)
  To: yijiangshan, jarkko, sashiko-bot; +Cc: stable


The patch below does not apply to the 7.2-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-7.2.y
git checkout FETCH_HEAD
git cherry-pick -x 9b522400bf5c082feb9a0037a053ea822a2c7e4d
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026100307-vacancy-udder-83a1@gregkh' --subject-prefix 'PATCH 7.2.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9b522400bf5c082feb9a0037a053ea822a2c7e4d Mon Sep 17 00:00:00 2001
From: Jiangshan Yi <yijiangshan@kylinos.cn>
Date: Thu, 3 Sep 2026 11:58:37 +0800
Subject: [PATCH] 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 <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260902074839.417419-1-yijiangshan%40kylinos.cn
Signed-off-by: Jiangshan Yi <yijiangshan@kylinos.cn>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lore.kernel.org/r/20260903035837.219284-1-yijiangshan@kylinos.cn
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

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);


^ permalink raw reply related	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2026-10-05 13:51 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-10-03 13:20 FAILED: patch "[PATCH] tpm: fix off-by-four bounds check in tpm2_get_random()" failed to apply to 7.2-stable tree gregkh
2026-10-04  1:39 ` [PATCH 7.2.y 1/8] tpm: Initial step to reorganize TPM public headers Sasha Levin
2026-10-04  1:39   ` [PATCH 7.2.y 2/8] tpm: Move TPM1 specific definitions to the command header Sasha Levin
2026-10-04  1:39   ` [PATCH 7.2.y 3/8] tpm: Move TPM2 " Sasha Levin
2026-10-04  1:39   ` [PATCH 7.2.y 4/8] tpm: Move TPM common base " Sasha Levin
2026-10-04  1:39   ` [PATCH 7.2.y 5/8] tpm-buf: Merge TPM_BUF_BOUNDARY_ERROR and TPM_BUF_OVERFLOW Sasha Levin
2026-10-04  1:40   ` [PATCH 7.2.y 6/8] tpm-buf: Remove chip parameter from tpm_buf_append_handle() Sasha Levin
2026-10-04  1:40   ` [PATCH 7.2.y 7/8] tpm-buf: Memory-safe allocations Sasha Levin
2026-10-04  1:40   ` [PATCH 7.2.y 8/8] tpm: fix off-by-four bounds check in tpm2_get_random() Sasha Levin
2026-10-05  7:54 ` [PATCH 7.2.y] " Jarkko Sakkinen
2026-10-05 13:50   ` Sasha Levin

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