| Message ID | 20220608131732.550234-1-niejianglei2021@163.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] KEYS: trusted: Fix memory leak in tpm2_key_encode() | expand |
On Wed, Jun 08, 2022 at 09:17:32PM +0800, Jianglei Nie wrote: > tpm2_key_encode() allocates a memory chunk from scratch with kmalloc(), > but it is never freed, which leads to a memory leak. Free the memory > chunk with kfree() in the return path. This change only does the kfree in the success path; "out" just returns the error without freeing the memory. > Signed-off-by: Jianglei Nie <niejianglei2021@163.com> > --- > security/keys/trusted-keys/trusted_tpm2.c | 23 +++++++++++++++++------ > 1 file changed, 17 insertions(+), 6 deletions(-) > > diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c > index 0165da386289..8b7ab22950d1 100644 > --- a/security/keys/trusted-keys/trusted_tpm2.c > +++ b/security/keys/trusted-keys/trusted_tpm2.c > @@ -32,6 +32,7 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > struct trusted_key_options *options, > u8 *src, u32 len) > { > + int err; > const int SCRATCH_SIZE = PAGE_SIZE; > u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); > u8 *work = scratch, *work1; > @@ -57,8 +58,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > unsigned char bool[3], *w = bool; > /* tag 0 is emptyAuth */ > w = asn1_encode_boolean(w, w + sizeof(bool), true); > - if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) > - return PTR_ERR(w); > + if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) { > + err = PTR_ERR(w); > + goto out; > + } > work = asn1_encode_tag(work, end_work, 0, bool, w - bool); > } > > @@ -69,8 +72,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > * trigger, so if it does there's something nefarious going on > */ > if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE, > - "BUG: scratch buffer is too small")) > - return -EINVAL; > + "BUG: scratch buffer is too small")) { > + err = -EINVAL; > + goto out; > + } > > work = asn1_encode_integer(work, end_work, options->keyhandle); > work = asn1_encode_octet_string(work, end_work, pub, pub_len); > @@ -79,10 +84,16 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > work1 = payload->blob; > work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob), > scratch, work - scratch); > - if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) > - return PTR_ERR(work1); > + if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) { > + err = -EINVAL; > + goto out; > + } > + kfree(scratch); > > return work1 - payload->blob; > + > +out: > + return err; > } > > struct tpm2_key_context { > -- > 2.25.1
On Wed, Jun 08, 2022 at 09:17:32PM +0800, Jianglei Nie wrote: > tpm2_key_encode() allocates a memory chunk from scratch with kmalloc(), > but it is never freed, which leads to a memory leak. Free the memory > chunk with kfree() in the return path. > > Signed-off-by: Jianglei Nie <niejianglei2021@163.com> > --- You should write down the changelog ere. No idea what changed from the previous version. > security/keys/trusted-keys/trusted_tpm2.c | 23 +++++++++++++++++------ > 1 file changed, 17 insertions(+), 6 deletions(-) > > diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c > index 0165da386289..8b7ab22950d1 100644 > --- a/security/keys/trusted-keys/trusted_tpm2.c > +++ b/security/keys/trusted-keys/trusted_tpm2.c > @@ -32,6 +32,7 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > struct trusted_key_options *options, > u8 *src, u32 len) > { > + int err; Declare as the last local variable (reverse christmas tree order). Also, I'd use "int ret" since in other functions that is used. > const int SCRATCH_SIZE = PAGE_SIZE; > u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); > u8 *work = scratch, *work1; > @@ -57,8 +58,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > unsigned char bool[3], *w = bool; > /* tag 0 is emptyAuth */ > w = asn1_encode_boolean(w, w + sizeof(bool), true); > - if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) > - return PTR_ERR(w); > + if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) { > + err = PTR_ERR(w); > + goto out; > + } > work = asn1_encode_tag(work, end_work, 0, bool, w - bool); > } > > @@ -69,8 +72,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > * trigger, so if it does there's something nefarious going on > */ > if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE, > - "BUG: scratch buffer is too small")) > - return -EINVAL; > + "BUG: scratch buffer is too small")) { > + err = -EINVAL; > + goto out; > + } > > work = asn1_encode_integer(work, end_work, options->keyhandle); > work = asn1_encode_octet_string(work, end_work, pub, pub_len); > @@ -79,10 +84,16 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > work1 = payload->blob; > work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob), > scratch, work - scratch); > - if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) > - return PTR_ERR(work1); > + if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) { > + err = -EINVAL; > + goto out; Why you are changing the return value from PTR_ERR(work1 to -EINVAL? > + } > + kfree(scratch); > > return work1 - payload->blob; > + > +out: Nit: err: It's only used for the error path. > + return err; > } > > struct tpm2_key_context { > -- > 2.25.1 > BR, Jarkko
On Thu, Jun 09, 2022 at 08:21:20AM +0300, Jarkko Sakkinen wrote: > On Wed, Jun 08, 2022 at 09:17:32PM +0800, Jianglei Nie wrote: > > tpm2_key_encode() allocates a memory chunk from scratch with kmalloc(), > > but it is never freed, which leads to a memory leak. Free the memory > > chunk with kfree() in the return path. > > > > Signed-off-by: Jianglei Nie <niejianglei2021@163.com> > > --- > > You should write down the changelog ere. No idea what changed > from the previous version. > > > security/keys/trusted-keys/trusted_tpm2.c | 23 +++++++++++++++++------ > > 1 file changed, 17 insertions(+), 6 deletions(-) > > > > diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c > > index 0165da386289..8b7ab22950d1 100644 > > --- a/security/keys/trusted-keys/trusted_tpm2.c > > +++ b/security/keys/trusted-keys/trusted_tpm2.c > > @@ -32,6 +32,7 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > > struct trusted_key_options *options, > > u8 *src, u32 len) > > { > > + int err; > > Declare as the last local variable (reverse christmas tree order). > > Also, I'd use "int ret" since in other functions that is used. > > > const int SCRATCH_SIZE = PAGE_SIZE; > > u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); > > u8 *work = scratch, *work1; > > @@ -57,8 +58,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > > unsigned char bool[3], *w = bool; > > /* tag 0 is emptyAuth */ > > w = asn1_encode_boolean(w, w + sizeof(bool), true); > > - if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) > > - return PTR_ERR(w); > > + if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) { > > + err = PTR_ERR(w); > > + goto out; > > + } > > work = asn1_encode_tag(work, end_work, 0, bool, w - bool); > > } > > > > @@ -69,8 +72,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > > * trigger, so if it does there's something nefarious going on > > */ > > if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE, > > - "BUG: scratch buffer is too small")) > > - return -EINVAL; > > + "BUG: scratch buffer is too small")) { > > + err = -EINVAL; > > + goto out; > > + } > > > > work = asn1_encode_integer(work, end_work, options->keyhandle); > > work = asn1_encode_octet_string(work, end_work, pub, pub_len); > > @@ -79,10 +84,16 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > > work1 = payload->blob; > > work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob), > > scratch, work - scratch); > > - if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) > > - return PTR_ERR(work1); > > + if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) { > > + err = -EINVAL; > > + goto out; > > Why you are changing the return value from PTR_ERR(work1 > to -EINVAL? > > > + } > > + kfree(scratch); > > > > return work1 - payload->blob; > > + > > +out: > > Nit: > > err: > > It's only used for the error path. > > > + return err; > > } > > > > struct tpm2_key_context { > > -- > > 2.25.1 > > > > BR, Jarkko And the patch is also missing fixes tag: Fixes: f2219745250f ("security: keys: trusted: use ASN.1 TPM2 key format for the blobs") BR, Jarkko
On Wed, Jun 08, 2022 at 01:38:35PM +0000, Jonathan McDowell wrote: > On Wed, Jun 08, 2022 at 09:17:32PM +0800, Jianglei Nie wrote: > > tpm2_key_encode() allocates a memory chunk from scratch with kmalloc(), > > but it is never freed, which leads to a memory leak. Free the memory > > chunk with kfree() in the return path. > > This change only does the kfree in the success path; "out" just returns > the error without freeing the memory. A valid point. > > Signed-off-by: Jianglei Nie <niejianglei2021@163.com> > > --- > > security/keys/trusted-keys/trusted_tpm2.c | 23 +++++++++++++++++------ > > 1 file changed, 17 insertions(+), 6 deletions(-) > > > > diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c > > index 0165da386289..8b7ab22950d1 100644 > > --- a/security/keys/trusted-keys/trusted_tpm2.c > > +++ b/security/keys/trusted-keys/trusted_tpm2.c > > @@ -32,6 +32,7 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > > struct trusted_key_options *options, > > u8 *src, u32 len) > > { > > + int err; > > const int SCRATCH_SIZE = PAGE_SIZE; > > u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); Also, the fix is half-way there, it does not have OOM check for scratch. I.e. I'd change the declaration as: u8 *scratch; And later on after declarations: scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); if (!scratch) return -ENOMEM; > > u8 *work = scratch, *work1; > > @@ -57,8 +58,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > > unsigned char bool[3], *w = bool; > > /* tag 0 is emptyAuth */ > > w = asn1_encode_boolean(w, w + sizeof(bool), true); > > - if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) > > - return PTR_ERR(w); > > + if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) { > > + err = PTR_ERR(w); > > + goto out; > > + } > > work = asn1_encode_tag(work, end_work, 0, bool, w - bool); > > } > > > > @@ -69,8 +72,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > > * trigger, so if it does there's something nefarious going on > > */ > > if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE, > > - "BUG: scratch buffer is too small")) > > - return -EINVAL; > > + "BUG: scratch buffer is too small")) { > > + err = -EINVAL; > > + goto out; > > + } > > > > work = asn1_encode_integer(work, end_work, options->keyhandle); > > work = asn1_encode_octet_string(work, end_work, pub, pub_len); > > @@ -79,10 +84,16 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > > work1 = payload->blob; > > work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob), > > scratch, work - scratch); > > - if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) > > - return PTR_ERR(work1); > > + if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) { > > + err = -EINVAL; > > + goto out; > > + } > > + kfree(scratch); > > > > return work1 - payload->blob; > > + > > +out: > > + return err; I.e. kfree(scratch); return work1 - payload->blob; err: kfree(scratch); return ret; > > } > > > > struct tpm2_key_context { > > -- > > 2.25.1 BR, Jarkko
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index 0165da386289..8b7ab22950d1 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -32,6 +32,7 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, struct trusted_key_options *options, u8 *src, u32 len) { + int err; const int SCRATCH_SIZE = PAGE_SIZE; u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); u8 *work = scratch, *work1; @@ -57,8 +58,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, unsigned char bool[3], *w = bool; /* tag 0 is emptyAuth */ w = asn1_encode_boolean(w, w + sizeof(bool), true); - if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) - return PTR_ERR(w); + if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) { + err = PTR_ERR(w); + goto out; + } work = asn1_encode_tag(work, end_work, 0, bool, w - bool); } @@ -69,8 +72,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, * trigger, so if it does there's something nefarious going on */ if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE, - "BUG: scratch buffer is too small")) - return -EINVAL; + "BUG: scratch buffer is too small")) { + err = -EINVAL; + goto out; + } work = asn1_encode_integer(work, end_work, options->keyhandle); work = asn1_encode_octet_string(work, end_work, pub, pub_len); @@ -79,10 +84,16 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, work1 = payload->blob; work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob), scratch, work - scratch); - if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) - return PTR_ERR(work1); + if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) { + err = -EINVAL; + goto out; + } + kfree(scratch); return work1 - payload->blob; + +out: + return err; } struct tpm2_key_context {
tpm2_key_encode() allocates a memory chunk from scratch with kmalloc(), but it is never freed, which leads to a memory leak. Free the memory chunk with kfree() in the return path. Signed-off-by: Jianglei Nie <niejianglei2021@163.com> --- security/keys/trusted-keys/trusted_tpm2.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-)