[PATCH] tpm2-sessions: Fix missing tpm_buf_destroy() in tpm2_read_public()

[PATCH] tpm2-sessions: Fix missing tpm_buf_destroy() in tpm2_read_public()

[Gunnar Kudrjavets]

tpm2_read_public() calls tpm_buf_init() but fails to call
tpm_buf_destroy() on two exit paths, leaking a page allocation:

1. When name_size() returns an error (unrecognized hash algorithm),
   the function returns directly without destroying the buffer.

2. On the success path, the buffer is never destroyed before
   returning.

All other error paths in the function correctly call
tpm_buf_destroy() before returning.

Fix both by adding the missing tpm_buf_destroy() calls.

Fixes: bda1cbf73c6e ("tpm2-sessions: Fix tpm2_read_public range checks")
Signed-off-by: Gunnar Kudrjavets <gunnarku@amazon.com>
Reviewed-by: Justinien Bouron <jbouron@amazon.com>
---
 drivers/char/tpm/tpm2-sessions.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 09df6353ef04..f7c6c043fef4 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -203,8 +203,10 @@ static int tpm2_read_public(struct tpm_chip *chip, u32 handle, void *name)
 	rc = tpm_buf_read_u16(&buf, &offset);
 	name_size_alg = name_size(&buf.data[offset]);
 
-	if (name_size_alg < 0)
+	if (name_size_alg < 0) {
+		tpm_buf_destroy(&buf);
 		return name_size_alg;
+	}
 
 	if (rc != name_size_alg) {
 		tpm_buf_destroy(&buf);
@@ -217,6 +219,7 @@ static int tpm2_read_public(struct tpm_chip *chip, u32 handle, void *name)
 	}
 
 	memcpy(name, &buf.data[offset], rc);
+	tpm_buf_destroy(&buf);
 	return name_size_alg;
 }
 #endif /* CONFIG_TCG_TPM2_HMAC */

base-commit: 03e5553f5fb99cb47c315e167a604a9c69e6f724
-- 
2.47.3

Re: [PATCH] tpm2-sessions: Fix missing tpm_buf_destroy() in tpm2_read_public()

[Paul Menzel]

Dear Gunnar,


Thank you for your patch.

Am 08.04.26 um 18:43 schrieb Gunnar Kudrjavets:
> tpm2_read_public() calls tpm_buf_init() but fails to call
> tpm_buf_destroy() on two exit paths, leaking a page allocation:
> 
> 1. When name_size() returns an error (unrecognized hash algorithm),
>     the function returns directly without destroying the buffer.
> 
> 2. On the success path, the buffer is never destroyed before
>     returning.
> 
> All other error paths in the function correctly call
> tpm_buf_destroy() before returning.
> 
> Fix both by adding the missing tpm_buf_destroy() calls.
> 
> Fixes: bda1cbf73c6e ("tpm2-sessions: Fix tpm2_read_public range checks")
> Signed-off-by: Gunnar Kudrjavets <gunnarku@amazon.com>
> Reviewed-by: Justinien Bouron <jbouron@amazon.com>
> ---
>   drivers/char/tpm/tpm2-sessions.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
> index 09df6353ef04..f7c6c043fef4 100644
> --- a/drivers/char/tpm/tpm2-sessions.c
> +++ b/drivers/char/tpm/tpm2-sessions.c
> @@ -203,8 +203,10 @@ static int tpm2_read_public(struct tpm_chip *chip, u32 handle, void *name)
>   	rc = tpm_buf_read_u16(&buf, &offset);
>   	name_size_alg = name_size(&buf.data[offset]);
>   
> -	if (name_size_alg < 0)
> +	if (name_size_alg < 0) {
> +		tpm_buf_destroy(&buf);
>   		return name_size_alg;
> +	}
>   
>   	if (rc != name_size_alg) {
>   		tpm_buf_destroy(&buf);
> @@ -217,6 +219,7 @@ static int tpm2_read_public(struct tpm_chip *chip, u32 handle, void *name)
>   	}
>   
>   	memcpy(name, &buf.data[offset], rc);
> +	tpm_buf_destroy(&buf);
>   	return name_size_alg;
>   }
>   #endif /* CONFIG_TCG_TPM2_HMAC */
> 
> base-commit: 03e5553f5fb99cb47c315e167a604a9c69e6f724

Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>


Kind regards,

Paul