kernel BUG at security/keys/keyring.c:LINE!

From: Eric Biggers <[email protected]>

syzbot hit the 'BUG_ON(index_key->desc_len = 0);' in __key_link_begin() called from construct_alloc_key() during sys_request_key(), because the length of the key description was never calculated.

The problem is that we rely on ->desc_len being initialized by search_process_keyrings(), specifically by search_nested_keyrings(). But, if the process isn't subscribed to any keyrings that never happens.

Fix it by always initializing keyring_index_key::desc_len as soon as the description is set, like we already do in some places.

The following program reproduces the BUG_ON() when it's run as root and no session keyring has been installed. If it doesn't work, try removing pam_keyinit.so from /etc/pam.d/login and rebooting.

    #include <stdlib.h>
    #include <unistd.h>
    #include <keyutils.h>

    int main(void)
    {
            int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING);

            keyctl_setperm(id, KEY_OTH_WRITE);
            setreuid(5000, 5000);
            request_key("user", "desc", "", id);
    }

Reported-by [email protected]

Fixes b2a4df200d57 ("KEYS: Expand the capacity of a keyring")

Cc <[email protected]> # v3.13+

Signed-off-by Eric Biggers <[email protected]>

---
 security/keys/keyring.c          | 4 +---
 security/keys/proc.c             | 1 +
 security/keys/request_key.c      | 1 +
 security/keys/request_key_auth.c | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

security/keys/keyring.c +1 -3

index 41bcf57e96f2..99a55145ddcd 100644
@@ -661,9 +661,6 @@ static bool search_nested_keyrings(struct key *keyring,
 	BUG_ON((ctx->flags & STATE_CHECKS) = 0 ||
 	       (ctx->flags & STATE_CHECKS) = STATE_CHECKS);
 
-	if (ctx->index_key.description)
-		ctx->index_key.desc_len = strlen(ctx->index_key.description);
-
 	/* Check to see if this top-level keyring is what we are looking for
 	 * and whether it is valid or not.
 	 */

@@ -914,6 +911,7 @@ key_ref_t keyring_search(key_ref_t keyring,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/proc.c +0 -0

index 5af2934965d8..909f6c5270a1 100644

From: Eric Biggers <[email protected]>

syzbot hit the 'BUG_ON(index_key->desc_len = 0);' in __key_link_begin() called from construct_alloc_key() during sys_request_key(), because the length of the key description was never calculated.

The problem is that we rely on ->desc_len being initialized by search_process_keyrings(), specifically by search_nested_keyrings(). But, if the process isn't subscribed to any keyrings that never happens.

Fix it by always initializing keyring_index_key::desc_len as soon as the description is set, like we already do in some places.

The following program reproduces the BUG_ON() when it's run as root and no session keyring has been installed. If it doesn't work, try removing pam_keyinit.so from /etc/pam.d/login and rebooting.

    #include <stdlib.h>
    #include <unistd.h>
    #include <keyutils.h>

    int main(void)
    {
            int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING);

            keyctl_setperm(id, KEY_OTH_WRITE);
            setreuid(5000, 5000);
            request_key("user", "desc", "", id);
    }

Reported-by [email protected]

Fixes b2a4df200d57 ("KEYS: Expand the capacity of a keyring")

Cc <[email protected]> # v3.13+

Signed-off-by Eric Biggers <[email protected]>

---

v2: In proc_keys_show(), assign index_key directly

 security/keys/keyring.c          | 4 +---
 security/keys/proc.c             | 3 +--
 security/keys/request_key.c      | 1 +
 security/keys/request_key_auth.c | 2 +-
 4 files changed, 4 insertions(+), 6 deletions(-)

security/keys/keyring.c +1 -3

index 41bcf57e96f21..99a55145ddcd2 100644
@@ -661,9 +661,6 @@ static bool search_nested_keyrings(struct key *keyring,
 	BUG_ON((ctx->flags & STATE_CHECKS) = 0 ||
 	       (ctx->flags & STATE_CHECKS) = STATE_CHECKS);
 
-	if (ctx->index_key.description)
-		ctx->index_key.desc_len = strlen(ctx->index_key.description);
-
 	/* Check to see if this top-level keyring is what we are looking for
 	 * and whether it is valid or not.
 	 */

@@ -914,6 +911,7 @@ key_ref_t keyring_search(key_ref_t keyring,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/proc.c +1 -2

index 5af2934965d80..d38be9db2cc07 100644
@@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
 	int rc;
 
 	struct keyring_search_context ctx = {
-		.index_key.type		= key->type,
-		.index_key.description	= key->description,
+		.index_key		= key->index_key,
 		.cred			= m->file->f_cred,
 		.match_data.cmp		= lookup_user_key_possessed,
 		.match_data.raw_data	= key,

security/keys/request_key.c +1 -0

index 114f7408feee6..7385536986497 100644
@@ -545,6 +545,7 @@ struct key *request_key_and_link(struct key_type *type,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/request_key_auth.c +1 -1

index 424e1d90412ea..6797843154f03 100644
@@ -246,7 +246,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id)
 	struct key *authkey;
 	key_ref_t authkey_ref;
 
-	sprintf(description, "%x", target_id);
+	ctx.index_key.desc_len = sprintf(description, "%x", target_id);
 
 	authkey_ref = search_process_keyrings(&ctx);
 

Signature · 1 line

2.19.1

Quoted 105 lines · Eric Biggers

From: Eric Biggers <[email protected]>

syzbot hit the 'BUG_ON(index_key->desc_len = 0);' in __key_link_begin() called from construct_alloc_key() during sys_request_key(), because the length of the key description was never calculated.

The problem is that we rely on ->desc_len being initialized by search_process_keyrings(), specifically by search_nested_keyrings(). But, if the process isn't subscribed to any keyrings that never happens.

Fix it by always initializing keyring_index_key::desc_len as soon as the description is set, like we already do in some places.

The following program reproduces the BUG_ON() when it's run as root and no session keyring has been installed. If it doesn't work, try removing pam_keyinit.so from /etc/pam.d/login and rebooting.

    #include <stdlib.h>
    #include <unistd.h>
    #include <keyutils.h>

    int main(void)
    {
            int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING);

            keyctl_setperm(id, KEY_OTH_WRITE);
            setreuid(5000, 5000);
            request_key("user", "desc", "", id);
    }

Reported-by [email protected]

Fixes b2a4df200d57 ("KEYS: Expand the capacity of a keyring")

Cc <[email protected]> # v3.13+

Signed-off-by Eric Biggers <[email protected]>

---

v2: In proc_keys_show(), assign index_key directly

 security/keys/keyring.c          | 4 +---
 security/keys/proc.c             | 3 +--
 security/keys/request_key.c      | 1 +
 security/keys/request_key_auth.c | 2 +-
 4 files changed, 4 insertions(+), 6 deletions(-)

security/keys/keyring.c +1 -3

index 41bcf57e96f21..99a55145ddcd2 100644
@@ -661,9 +661,6 @@ static bool search_nested_keyrings(struct key *keyring,
 	BUG_ON((ctx->flags & STATE_CHECKS) = 0 ||
 	       (ctx->flags & STATE_CHECKS) = STATE_CHECKS);
 
-	if (ctx->index_key.description)
-		ctx->index_key.desc_len = strlen(ctx->index_key.description);
-
 	/* Check to see if this top-level keyring is what we are looking for
 	 * and whether it is valid or not.
 	 */

@@ -914,6 +911,7 @@ key_ref_t keyring_search(key_ref_t keyring,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/proc.c +1 -2

index 5af2934965d80..d38be9db2cc07 100644
@@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
 	int rc;
 
 	struct keyring_search_context ctx = {
-		.index_key.type		= key->type,
-		.index_key.description	= key->description,
+		.index_key		= key->index_key,
 		.cred			= m->file->f_cred,
 		.match_data.cmp		= lookup_user_key_possessed,
 		.match_data.raw_data	= key,

security/keys/request_key.c +1 -0

index 114f7408feee6..7385536986497 100644
@@ -545,6 +545,7 @@ struct key *request_key_and_link(struct key_type *type,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/request_key_auth.c +1 -1

index 424e1d90412ea..6797843154f03 100644
@@ -246,7 +246,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id)
 	struct key *authkey;
 	key_ref_t authkey_ref;
 
-	sprintf(description, "%x", target_id);
+	ctx.index_key.desc_len = sprintf(description, "%x", target_id);
 
 	authkey_ref = search_process_keyrings(&ctx);
 

Quoted 3 lines

Signature · 1 line

2.19.1

Ping. David, are you planning to apply this?

- Eric

Quoted 105 lines · Eric Biggers

From: Eric Biggers <[email protected]>

syzbot hit the 'BUG_ON(index_key->desc_len = 0);' in __key_link_begin() called from construct_alloc_key() during sys_request_key(), because the length of the key description was never calculated.

The problem is that we rely on ->desc_len being initialized by search_process_keyrings(), specifically by search_nested_keyrings(). But, if the process isn't subscribed to any keyrings that never happens.

Fix it by always initializing keyring_index_key::desc_len as soon as the description is set, like we already do in some places.

The following program reproduces the BUG_ON() when it's run as root and no session keyring has been installed. If it doesn't work, try removing pam_keyinit.so from /etc/pam.d/login and rebooting.

    #include <stdlib.h>
    #include <unistd.h>
    #include <keyutils.h>

    int main(void)
    {
            int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING);

            keyctl_setperm(id, KEY_OTH_WRITE);
            setreuid(5000, 5000);
            request_key("user", "desc", "", id);
    }

Reported-by [email protected]

Fixes b2a4df200d57 ("KEYS: Expand the capacity of a keyring")

Cc <[email protected]> # v3.13+

Signed-off-by Eric Biggers <[email protected]>

---

v2: In proc_keys_show(), assign index_key directly

 security/keys/keyring.c          | 4 +---
 security/keys/proc.c             | 3 +--
 security/keys/request_key.c      | 1 +
 security/keys/request_key_auth.c | 2 +-
 4 files changed, 4 insertions(+), 6 deletions(-)

security/keys/keyring.c +1 -3

index 41bcf57e96f21..99a55145ddcd2 100644
@@ -661,9 +661,6 @@ static bool search_nested_keyrings(struct key *keyring,
 	BUG_ON((ctx->flags & STATE_CHECKS) = 0 ||
 	       (ctx->flags & STATE_CHECKS) = STATE_CHECKS);
 
-	if (ctx->index_key.description)
-		ctx->index_key.desc_len = strlen(ctx->index_key.description);
-
 	/* Check to see if this top-level keyring is what we are looking for
 	 * and whether it is valid or not.
 	 */

@@ -914,6 +911,7 @@ key_ref_t keyring_search(key_ref_t keyring,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/proc.c +1 -2

index 5af2934965d80..d38be9db2cc07 100644
@@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
 	int rc;
 
 	struct keyring_search_context ctx = {
-		.index_key.type		= key->type,
-		.index_key.description	= key->description,
+		.index_key		= key->index_key,
 		.cred			= m->file->f_cred,
 		.match_data.cmp		= lookup_user_key_possessed,
 		.match_data.raw_data	= key,

security/keys/request_key.c +1 -0

index 114f7408feee6..7385536986497 100644
@@ -545,6 +545,7 @@ struct key *request_key_and_link(struct key_type *type,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/request_key_auth.c +1 -1

index 424e1d90412ea..6797843154f03 100644
@@ -246,7 +246,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id)
 	struct key *authkey;
 	key_ref_t authkey_ref;
 
-	sprintf(description, "%x", target_id);
+	ctx.index_key.desc_len = sprintf(description, "%x", target_id);
 
 	authkey_ref = search_process_keyrings(&ctx);
 

Quoted 3 lines

Signature · 1 line

2.19.1

Ping. David, are you planning to apply this?

- Eric

Signature · 4 lines

You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20181128231940.GB131170%40gmail.com.
For more options, visit https://groups.google.com/d/optout.

Quoted 114 lines · Eric Biggers

Quoted 108 lines · Eric Biggers

From: Eric Biggers <[email protected]>

syzbot hit the 'BUG_ON(index_key->desc_len = 0);' in __key_link_begin() called from construct_alloc_key() during sys_request_key(), because the length of the key description was never calculated.

The problem is that we rely on ->desc_len being initialized by search_process_keyrings(), specifically by search_nested_keyrings(). But, if the process isn't subscribed to any keyrings that never happens.

Fix it by always initializing keyring_index_key::desc_len as soon as the description is set, like we already do in some places.

The following program reproduces the BUG_ON() when it's run as root and no session keyring has been installed. If it doesn't work, try removing pam_keyinit.so from /etc/pam.d/login and rebooting.

    #include <stdlib.h>
    #include <unistd.h>
    #include <keyutils.h>

    int main(void)
    {
            int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING);

            keyctl_setperm(id, KEY_OTH_WRITE);
            setreuid(5000, 5000);
            request_key("user", "desc", "", id);
    }

Reported-by [email protected]

Fixes b2a4df200d57 ("KEYS: Expand the capacity of a keyring")

Cc <[email protected]> # v3.13+

Signed-off-by Eric Biggers <[email protected]>

---

v2: In proc_keys_show(), assign index_key directly

 security/keys/keyring.c          | 4 +---
 security/keys/proc.c             | 3 +--
 security/keys/request_key.c      | 1 +
 security/keys/request_key_auth.c | 2 +-
 4 files changed, 4 insertions(+), 6 deletions(-)

security/keys/keyring.c +1 -3

index 41bcf57e96f21..99a55145ddcd2 100644
@@ -661,9 +661,6 @@ static bool search_nested_keyrings(struct key *keyring,
 	BUG_ON((ctx->flags & STATE_CHECKS) = 0 ||
 	       (ctx->flags & STATE_CHECKS) = STATE_CHECKS);
 
-	if (ctx->index_key.description)
-		ctx->index_key.desc_len = strlen(ctx->index_key.description);
-
 	/* Check to see if this top-level keyring is what we are looking for
 	 * and whether it is valid or not.
 	 */

@@ -914,6 +911,7 @@ key_ref_t keyring_search(key_ref_t keyring,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/proc.c +1 -2

index 5af2934965d80..d38be9db2cc07 100644
@@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
 	int rc;
 
 	struct keyring_search_context ctx = {
-		.index_key.type		= key->type,
-		.index_key.description	= key->description,
+		.index_key		= key->index_key,
 		.cred			= m->file->f_cred,
 		.match_data.cmp		= lookup_user_key_possessed,
 		.match_data.raw_data	= key,

security/keys/request_key.c +1 -0

index 114f7408feee6..7385536986497 100644
@@ -545,6 +545,7 @@ struct key *request_key_and_link(struct key_type *type,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/request_key_auth.c +1 -1

index 424e1d90412ea..6797843154f03 100644
@@ -246,7 +246,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id)
 	struct key *authkey;
 	key_ref_t authkey_ref;
 
-	sprintf(description, "%x", target_id);
+	ctx.index_key.desc_len = sprintf(description, "%x", target_id);
 
 	authkey_ref = search_process_keyrings(&ctx);
 

Signature · 1 line

2.19.1

Ping. David, are you planning to apply this?

- Eric

Quoted 5 lines

Signature · 4 lines

You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20181128231940.GB131170%40gmail.com.
For more options, visit https://groups.google.com/d/optout.

Ping.

Quoted 121 lines · Eric Biggers

Quoted 119 lines · Eric Biggers

Quoted 108 lines · Eric Biggers

From: Eric Biggers <[email protected]>

syzbot hit the 'BUG_ON(index_key->desc_len = 0);' in __key_link_begin() called from construct_alloc_key() during sys_request_key(), because the length of the key description was never calculated.

The problem is that we rely on ->desc_len being initialized by search_process_keyrings(), specifically by search_nested_keyrings(). But, if the process isn't subscribed to any keyrings that never happens.

Fix it by always initializing keyring_index_key::desc_len as soon as the description is set, like we already do in some places.

The following program reproduces the BUG_ON() when it's run as root and no session keyring has been installed. If it doesn't work, try removing pam_keyinit.so from /etc/pam.d/login and rebooting.

    #include <stdlib.h>
    #include <unistd.h>
    #include <keyutils.h>

    int main(void)
    {
            int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING);

            keyctl_setperm(id, KEY_OTH_WRITE);
            setreuid(5000, 5000);
            request_key("user", "desc", "", id);
    }

Reported-by [email protected]

Fixes b2a4df200d57 ("KEYS: Expand the capacity of a keyring")

Cc <[email protected]> # v3.13+

Signed-off-by Eric Biggers <[email protected]>

---

v2: In proc_keys_show(), assign index_key directly

 security/keys/keyring.c          | 4 +---
 security/keys/proc.c             | 3 +--
 security/keys/request_key.c      | 1 +
 security/keys/request_key_auth.c | 2 +-
 4 files changed, 4 insertions(+), 6 deletions(-)

security/keys/keyring.c +1 -3

index 41bcf57e96f21..99a55145ddcd2 100644
@@ -661,9 +661,6 @@ static bool search_nested_keyrings(struct key *keyring,
 	BUG_ON((ctx->flags & STATE_CHECKS) = 0 ||
 	       (ctx->flags & STATE_CHECKS) = STATE_CHECKS);
 
-	if (ctx->index_key.description)
-		ctx->index_key.desc_len = strlen(ctx->index_key.description);
-
 	/* Check to see if this top-level keyring is what we are looking for
 	 * and whether it is valid or not.
 	 */

@@ -914,6 +911,7 @@ key_ref_t keyring_search(key_ref_t keyring,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/proc.c +1 -2

index 5af2934965d80..d38be9db2cc07 100644
@@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
 	int rc;
 
 	struct keyring_search_context ctx = {
-		.index_key.type		= key->type,
-		.index_key.description	= key->description,
+		.index_key		= key->index_key,
 		.cred			= m->file->f_cred,
 		.match_data.cmp		= lookup_user_key_possessed,
 		.match_data.raw_data	= key,

security/keys/request_key.c +1 -0

index 114f7408feee6..7385536986497 100644
@@ -545,6 +545,7 @@ struct key *request_key_and_link(struct key_type *type,
 	struct keyring_search_context ctx = {
 		.index_key.type		= type,
 		.index_key.description	= description,
+		.index_key.desc_len	= strlen(description),
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,

security/keys/request_key_auth.c +1 -1

index 424e1d90412ea..6797843154f03 100644
@@ -246,7 +246,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id)
 	struct key *authkey;
 	key_ref_t authkey_ref;
 
-	sprintf(description, "%x", target_id);
+	ctx.index_key.desc_len = sprintf(description, "%x", target_id);
 
 	authkey_ref = search_process_keyrings(&ctx);
 

Signature · 1 line

2.19.1

Ping. David, are you planning to apply this?

- Eric

Signature · 4 lines

You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20181128231940.GB131170%40gmail.com.
For more options, visit https://groups.google.com/d/optout.

Quoted 2 lines

Ping.

Ping. David, are you planning to apply this?

- Eric