| Message ID | 20240311211946.2691879-1-jwcart2@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | c205b924e280 |
| Delegated to: | Petr Lautrbach |
| Headers | show |
| Series | [v2] libsepol: Fix buffer overflow when using sepol_av_to_string() | expand |
On Mon, Mar 11, 2024 at 5:19 PM James Carter <jwcart2@gmail.com> wrote: > > The function sepol_av_to_string() normally returns a list of > permissions with a space at the beginning, but it will return '\0' > if there are no permissions. Unfortunately, functions in > kernel_to_cil, kernel_to_conf, and module_to_cil assume there is a > space at the beginning and skip the space by using "perms+1". > > In kernel_to_cil, kernel_to_conf, and module_to_cil, check for the > permission string being '\0' and return an error if it is. > > Reported-by: oss-fuzz (issue 67276) > Signed-off-by: James Carter <jwcart2@gmail.com> This patch has been merged. Jim > --- > libsepol/src/kernel_to_cil.c | 11 +++++++++++ > libsepol/src/kernel_to_conf.c | 11 +++++++++++ > libsepol/src/module_to_cil.c | 12 ++++++++++++ > 3 files changed, 34 insertions(+) > > diff --git a/libsepol/src/kernel_to_cil.c b/libsepol/src/kernel_to_cil.c > index a081915e..e20ba4af 100644 > --- a/libsepol/src/kernel_to_cil.c > +++ b/libsepol/src/kernel_to_cil.c > @@ -302,6 +302,12 @@ static int class_constraint_rules_to_strs(struct policydb *pdb, char *classkey, > rc = -1; > goto exit; > } > + if (*perms == '\0') { > + ERR(NULL, "No permisisons in permission string"); > + free(perms); > + rc = -1; > + goto exit; > + } > > if (is_mls) { > key_word = "mlsconstrain"; > @@ -1775,6 +1781,11 @@ static char *avtab_node_to_str(struct policydb *pdb, avtab_key_t *key, avtab_dat > ERR(NULL, "Failed to generate permission string"); > goto exit; > } > + if (*perms == '\0') { > + ERR(NULL, "No permisisons in permission string"); > + free(perms); > + goto exit; > + } > rule = create_str("(%s %s %s (%s (%s)))", > flavor, src, tgt, class, perms+1); > free(perms); > diff --git a/libsepol/src/kernel_to_conf.c b/libsepol/src/kernel_to_conf.c > index 956fb6e8..5860a513 100644 > --- a/libsepol/src/kernel_to_conf.c > +++ b/libsepol/src/kernel_to_conf.c > @@ -297,6 +297,12 @@ static int class_constraint_rules_to_strs(struct policydb *pdb, char *classkey, > rc = -1; > goto exit; > } > + if (*perms == '\0') { > + ERR(NULL, "No permisisons in permission string"); > + free(perms); > + rc = -1; > + goto exit; > + } > if (strchr(perms, ' ')) { > perm_prefix = "{ "; > perm_suffix = " }"; > @@ -1741,6 +1747,11 @@ static char *avtab_node_to_str(struct policydb *pdb, avtab_key_t *key, avtab_dat > ERR(NULL, "Failed to generate permission string"); > goto exit; > } > + if (*permstring == '\0') { > + ERR(NULL, "No permisisons in permission string"); > + free(permstring); > + goto exit; > + } > rule = create_str("%s %s %s:%s { %s };", > flavor, src, tgt, class, permstring+1); > free(permstring); > diff --git a/libsepol/src/module_to_cil.c b/libsepol/src/module_to_cil.c > index 6699a46b..3b3480bf 100644 > --- a/libsepol/src/module_to_cil.c > +++ b/libsepol/src/module_to_cil.c > @@ -593,6 +593,12 @@ static int avrule_to_cil(int indent, struct policydb *pdb, uint32_t type, const > rc = -1; > goto exit; > } > + if (*perms == '\0') { > + ERR(NULL, "No permissions in permission string"); > + free(perms); > + rc = -1; > + goto exit; > + } > cil_println(indent, "(%s %s %s (%s (%s)))", > rule, src, tgt, > pdb->p_class_val_to_name[classperm->tclass - 1], > @@ -1973,6 +1979,12 @@ static int constraints_to_cil(int indent, struct policydb *pdb, char *classkey, > rc = -1; > goto exit; > } > + if (*perms == '\0') { > + ERR(NULL, "No permissions in permission string"); > + free(perms); > + rc = -1; > + goto exit; > + } > cil_println(indent, "(%sconstrain (%s (%s)) %s)", mls, classkey, perms + 1, expr); > free(perms); > } else { > -- > 2.44.0 >
diff --git a/libsepol/src/kernel_to_cil.c b/libsepol/src/kernel_to_cil.c index a081915e..e20ba4af 100644 --- a/libsepol/src/kernel_to_cil.c +++ b/libsepol/src/kernel_to_cil.c @@ -302,6 +302,12 @@ static int class_constraint_rules_to_strs(struct policydb *pdb, char *classkey, rc = -1; goto exit; } + if (*perms == '\0') { + ERR(NULL, "No permisisons in permission string"); + free(perms); + rc = -1; + goto exit; + } if (is_mls) { key_word = "mlsconstrain"; @@ -1775,6 +1781,11 @@ static char *avtab_node_to_str(struct policydb *pdb, avtab_key_t *key, avtab_dat ERR(NULL, "Failed to generate permission string"); goto exit; } + if (*perms == '\0') { + ERR(NULL, "No permisisons in permission string"); + free(perms); + goto exit; + } rule = create_str("(%s %s %s (%s (%s)))", flavor, src, tgt, class, perms+1); free(perms); diff --git a/libsepol/src/kernel_to_conf.c b/libsepol/src/kernel_to_conf.c index 956fb6e8..5860a513 100644 --- a/libsepol/src/kernel_to_conf.c +++ b/libsepol/src/kernel_to_conf.c @@ -297,6 +297,12 @@ static int class_constraint_rules_to_strs(struct policydb *pdb, char *classkey, rc = -1; goto exit; } + if (*perms == '\0') { + ERR(NULL, "No permisisons in permission string"); + free(perms); + rc = -1; + goto exit; + } if (strchr(perms, ' ')) { perm_prefix = "{ "; perm_suffix = " }"; @@ -1741,6 +1747,11 @@ static char *avtab_node_to_str(struct policydb *pdb, avtab_key_t *key, avtab_dat ERR(NULL, "Failed to generate permission string"); goto exit; } + if (*permstring == '\0') { + ERR(NULL, "No permisisons in permission string"); + free(permstring); + goto exit; + } rule = create_str("%s %s %s:%s { %s };", flavor, src, tgt, class, permstring+1); free(permstring); diff --git a/libsepol/src/module_to_cil.c b/libsepol/src/module_to_cil.c index 6699a46b..3b3480bf 100644 --- a/libsepol/src/module_to_cil.c +++ b/libsepol/src/module_to_cil.c @@ -593,6 +593,12 @@ static int avrule_to_cil(int indent, struct policydb *pdb, uint32_t type, const rc = -1; goto exit; } + if (*perms == '\0') { + ERR(NULL, "No permissions in permission string"); + free(perms); + rc = -1; + goto exit; + } cil_println(indent, "(%s %s %s (%s (%s)))", rule, src, tgt, pdb->p_class_val_to_name[classperm->tclass - 1], @@ -1973,6 +1979,12 @@ static int constraints_to_cil(int indent, struct policydb *pdb, char *classkey, rc = -1; goto exit; } + if (*perms == '\0') { + ERR(NULL, "No permissions in permission string"); + free(perms); + rc = -1; + goto exit; + } cil_println(indent, "(%sconstrain (%s (%s)) %s)", mls, classkey, perms + 1, expr); free(perms); } else {
The function sepol_av_to_string() normally returns a list of permissions with a space at the beginning, but it will return '\0' if there are no permissions. Unfortunately, functions in kernel_to_cil, kernel_to_conf, and module_to_cil assume there is a space at the beginning and skip the space by using "perms+1". In kernel_to_cil, kernel_to_conf, and module_to_cil, check for the permission string being '\0' and return an error if it is. Reported-by: oss-fuzz (issue 67276) Signed-off-by: James Carter <jwcart2@gmail.com> --- libsepol/src/kernel_to_cil.c | 11 +++++++++++ libsepol/src/kernel_to_conf.c | 11 +++++++++++ libsepol/src/module_to_cil.c | 12 ++++++++++++ 3 files changed, 34 insertions(+)