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FAILED: patch "[PATCH] KEYS: trusted_tpm1: Compare HMAC values in constant time" failed to apply to 5.10-stable tree

PATCH New [email protected] 2 participants 2 messages Oct 16, 2025 – Oct 20, 2025

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Stable branch Security (LSM) Keys-trusted Keys/keyrings
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author maintainer
#0 lore raw

The patch below does not apply to the 5.10-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 <[email protected]>.

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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x eed0e3d305530066b4fc5370107cff8ef1a0d229
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025101623-bleep-cold-406b@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From eed0e3d305530066b4fc5370107cff8ef1a0d229 Mon Sep 17 00:00:00 2001
From: Eric Biggers <[email protected]>
Date: Sat, 9 Aug 2025 10:19:39 -0700
Subject: [PATCH] KEYS: trusted_tpm1: Compare HMAC values in constant time

To prevent timing attacks, HMAC value comparison needs to be constant time. Replace the memcmp() with the correct function, crypto_memneq().

[For the Fixes commit I used the commit that introduced the memcmp(). It predates the introduction of crypto_memneq(), but it was still a bug at the time even though a helper function didn't exist yet.]

Fixes d00a1c72f7f4 ("keys: add new trusted key-type")
Cc [email protected]
Signed-off-by Eric Biggers <[email protected]>
Reviewed-by Jarkko Sakkinen <[email protected]>
Signed-off-by Jarkko Sakkinen <[email protected]>
security/keys/trusted-keys/trusted_tpm1.c +4 -3
index 89c9798d1800..e73f2c6c817a 100644
@@ -7,6 +7,7 @@
  */
 
 #include <crypto/hash_info.h>
+#include <crypto/utils.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/parser.h>

@@ -241,7 +242,7 @@ int TSS_checkhmac1(unsigned char *buffer,
 	if (ret < 0)
 		goto out;
 
-	if (memcmp(testhmac, authdata, SHA1_DIGEST_SIZE))
+	if (crypto_memneq(testhmac, authdata, SHA1_DIGEST_SIZE))
 		ret = -EINVAL;
 out:
 	kfree_sensitive(sdesc);

@@ -334,7 +335,7 @@ static int TSS_checkhmac2(unsigned char *buffer,
 			  TPM_NONCE_SIZE, ononce, 1, continueflag1, 0, 0);
 	if (ret < 0)
 		goto out;
-	if (memcmp(testhmac1, authdata1, SHA1_DIGEST_SIZE)) {
+	if (crypto_memneq(testhmac1, authdata1, SHA1_DIGEST_SIZE)) {
 		ret = -EINVAL;
 		goto out;
 	}

@@ -343,7 +344,7 @@ static int TSS_checkhmac2(unsigned char *buffer,
 			  TPM_NONCE_SIZE, ononce, 1, continueflag2, 0, 0);
 	if (ret < 0)
 		goto out;
-	if (memcmp(testhmac2, authdata2, SHA1_DIGEST_SIZE))
+	if (crypto_memneq(testhmac2, authdata2, SHA1_DIGEST_SIZE))
 		ret = -EINVAL;
 out:
 	kfree_sensitive(sdesc);
maintainer
#1 lore raw

PATCH 1/1 KEYS: trusted_tpm1: Compare HMAC values in constant time

From: Eric Biggers <[email protected]>

[ Upstream commit eed0e3d305530066b4fc5370107cff8ef1a0d229 ]

To prevent timing attacks, HMAC value comparison needs to be constant time. Replace the memcmp() with the correct function, crypto_memneq().

[For the Fixes commit I used the commit that introduced the memcmp(). It predates the introduction of crypto_memneq(), but it was still a bug at the time even though a helper function didn't exist yet.]

Fixes d00a1c72f7f4 ("keys: add new trusted key-type")
Cc [email protected]
Signed-off-by Eric Biggers <[email protected]>
Reviewed-by Jarkko Sakkinen <[email protected]>
Signed-off-by Jarkko Sakkinen <[email protected]>
[ replaced crypto/utils.h include with crypto/algapi.h ]
Signed-off-by Sasha Levin <[email protected]>
---
 security/keys/trusted-keys/trusted_tpm1.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
security/keys/trusted-keys/trusted_tpm1.c +4 -3
index 4c3cffcd296ac..3e9dc03d59c91 100644
@@ -9,6 +9,7 @@
  */
 
 #include <crypto/hash_info.h>
+#include <crypto/algapi.h>
 #include <linux/uaccess.h>
 #include <linux/module.h>
 #include <linux/init.h>

@@ -248,7 +249,7 @@ int TSS_checkhmac1(unsigned char *buffer,
 	if (ret < 0)
 		goto out;
 
-	if (memcmp(testhmac, authdata, SHA1_DIGEST_SIZE))
+	if (crypto_memneq(testhmac, authdata, SHA1_DIGEST_SIZE))
 		ret = -EINVAL;
 out:
 	kfree_sensitive(sdesc);

@@ -341,7 +342,7 @@ static int TSS_checkhmac2(unsigned char *buffer,
 			  TPM_NONCE_SIZE, ononce, 1, continueflag1, 0, 0);
 	if (ret < 0)
 		goto out;
-	if (memcmp(testhmac1, authdata1, SHA1_DIGEST_SIZE)) {
+	if (crypto_memneq(testhmac1, authdata1, SHA1_DIGEST_SIZE)) {
 		ret = -EINVAL;
 		goto out;
 	}

@@ -350,7 +351,7 @@ static int TSS_checkhmac2(unsigned char *buffer,
 			  TPM_NONCE_SIZE, ononce, 1, continueflag2, 0, 0);
 	if (ret < 0)
 		goto out;
-	if (memcmp(testhmac2, authdata2, SHA1_DIGEST_SIZE))
+	if (crypto_memneq(testhmac2, authdata2, SHA1_DIGEST_SIZE))
 		ret = -EINVAL;
 out:
 	kfree_sensitive(sdesc);
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