| Message ID | 20191021152348.3906-1-navid.emamdoost@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] apparmor: Fix use-after-free in aa_audit_rule_init | expand |
On 2019-10-21 10:23:47, Navid Emamdoost wrote: > In the implementation of aa_audit_rule_init(), when aa_label_parse() > fails the allocated memory for rule is released using > aa_audit_rule_free(). But after this release, the return statement > tries to access the label field of the rule which results in > use-after-free. Before releasing the rule, copy errNo and return it > after release. > > Fixes: 52e8c38001d8 ("apparmor: Fix memory leak of rule on error exit path") Ugh! I'm not sure what I was thinking when I authored that patch. :/ > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> > --- > Changes in v2: > -- Fix typo in description > -- move err definition inside the if statement. > > security/apparmor/audit.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/security/apparmor/audit.c b/security/apparmor/audit.c > index 5a98661a8b46..334065302fb6 100644 > --- a/security/apparmor/audit.c > +++ b/security/apparmor/audit.c > @@ -197,8 +197,9 @@ int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) > rule->label = aa_label_parse(&root_ns->unconfined->label, rulestr, > GFP_KERNEL, true, false); > if (IS_ERR(rule->label)) { > + int err = rule->label; Since rule->label is a pointer, I'd like to see this: int err = PTR_ERR(rule->label); > aa_audit_rule_free(rule); > - return PTR_ERR(rule->label); > + return PTR_ERR(err); This line would change to: return err; Tyler > } > > *vrule = rule; > -- > 2.17.1 >
On Mon, Oct 21, 2019 at 10:45 AM Tyler Hicks <tyhicks@canonical.com> wrote: > > On 2019-10-21 10:23:47, Navid Emamdoost wrote: > > In the implementation of aa_audit_rule_init(), when aa_label_parse() > > fails the allocated memory for rule is released using > > aa_audit_rule_free(). But after this release, the return statement > > tries to access the label field of the rule which results in > > use-after-free. Before releasing the rule, copy errNo and return it > > after release. > > > > Fixes: 52e8c38001d8 ("apparmor: Fix memory leak of rule on error exit path") > > Ugh! I'm not sure what I was thinking when I authored that patch. :/ > > > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> > > --- > > Changes in v2: > > -- Fix typo in description > > -- move err definition inside the if statement. > > > > security/apparmor/audit.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/security/apparmor/audit.c b/security/apparmor/audit.c > > index 5a98661a8b46..334065302fb6 100644 > > --- a/security/apparmor/audit.c > > +++ b/security/apparmor/audit.c > > @@ -197,8 +197,9 @@ int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) > > rule->label = aa_label_parse(&root_ns->unconfined->label, rulestr, > > GFP_KERNEL, true, false); > > if (IS_ERR(rule->label)) { > > + int err = rule->label; > > Since rule->label is a pointer, I'd like to see this: > > int err = PTR_ERR(rule->label); > > > aa_audit_rule_free(rule); > > - return PTR_ERR(rule->label); > > + return PTR_ERR(err); > > This line would change to: > > return err; > Tyler, I made the changes and sent v3. > > Tyler > > > } > > > > *vrule = rule; > > -- > > 2.17.1 > >
diff --git a/security/apparmor/audit.c b/security/apparmor/audit.c index 5a98661a8b46..334065302fb6 100644 --- a/security/apparmor/audit.c +++ b/security/apparmor/audit.c @@ -197,8 +197,9 @@ int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) rule->label = aa_label_parse(&root_ns->unconfined->label, rulestr, GFP_KERNEL, true, false); if (IS_ERR(rule->label)) { + int err = rule->label; aa_audit_rule_free(rule); - return PTR_ERR(rule->label); + return PTR_ERR(err); } *vrule = rule;
In the implementation of aa_audit_rule_init(), when aa_label_parse() fails the allocated memory for rule is released using aa_audit_rule_free(). But after this release, the return statement tries to access the label field of the rule which results in use-after-free. Before releasing the rule, copy errNo and return it after release. Fixes: 52e8c38001d8 ("apparmor: Fix memory leak of rule on error exit path") Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> --- Changes in v2: -- Fix typo in description -- move err definition inside the if statement. security/apparmor/audit.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)