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authorArnd Bergmann <arnd@arndb.de>2017-09-15 22:55:46 +0300
committerJohn Johansen <john.johansen@canonical.com>2017-11-21 13:15:50 +0300
commit7bba39ae52c4d7b467d0a6f74cc067a561aac043 (patch)
tree3995a82c162d555bfdfc8901655fb19e852b0090 /security
parent5933a62708fbae49931694314f3c98fbe91bb178 (diff)
downloadlinux-7bba39ae52c4d7b467d0a6f74cc067a561aac043.tar.xz
apparmor: initialized returned struct aa_perms
gcc-4.4 points out suspicious code in compute_mnt_perms, where the aa_perms structure is only partially initialized before getting returned: security/apparmor/mount.c: In function 'compute_mnt_perms': security/apparmor/mount.c:227: error: 'perms.prompt' is used uninitialized in this function security/apparmor/mount.c:227: error: 'perms.hide' is used uninitialized in this function security/apparmor/mount.c:227: error: 'perms.cond' is used uninitialized in this function security/apparmor/mount.c:227: error: 'perms.complain' is used uninitialized in this function security/apparmor/mount.c:227: error: 'perms.stop' is used uninitialized in this function security/apparmor/mount.c:227: error: 'perms.deny' is used uninitialized in this function Returning or assigning partially initialized structures is a bit tricky, in particular it is explicitly allowed in c99 to assign a partially initialized structure to another, as long as only members are read that have been initialized earlier. Looking at what various compilers do here, the version that produced the warning copied uninitialized stack data, while newer versions (and also clang) either set the other members to zero or don't update the parts of the return buffer that are not modified in the temporary structure, but they never warn about this. In case of apparmor, it seems better to be a little safer and always initialize the aa_perms structure. Most users already do that, this changes the remaining ones, including the one instance that I got the warning for. Fixes: fa488437d0f9 ("apparmor: add mount mediation") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Seth Arnold <seth.arnold@canonical.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: John Johansen <john.johansen@canonical.com>
Diffstat (limited to 'security')
-rw-r--r--security/apparmor/file.c8
-rw-r--r--security/apparmor/lib.c13
-rw-r--r--security/apparmor/mount.c13
3 files changed, 12 insertions, 22 deletions
diff --git a/security/apparmor/file.c b/security/apparmor/file.c
index 3382518b87fa..e79bf44396a3 100644
--- a/security/apparmor/file.c
+++ b/security/apparmor/file.c
@@ -226,18 +226,12 @@ static u32 map_old_perms(u32 old)
struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
struct path_cond *cond)
{
- struct aa_perms perms;
-
/* FIXME: change over to new dfa format
* currently file perms are encoded in the dfa, new format
* splits the permissions from the dfa. This mapping can be
* done at profile load
*/
- perms.deny = 0;
- perms.kill = perms.stop = 0;
- perms.complain = perms.cond = 0;
- perms.hide = 0;
- perms.prompt = 0;
+ struct aa_perms perms = { };
if (uid_eq(current_fsuid(), cond->uid)) {
perms.allow = map_old_perms(dfa_user_allow(dfa, state));
diff --git a/security/apparmor/lib.c b/security/apparmor/lib.c
index 08ca26bcca77..3d0a2bf87abd 100644
--- a/security/apparmor/lib.c
+++ b/security/apparmor/lib.c
@@ -317,14 +317,11 @@ static u32 map_other(u32 x)
void aa_compute_perms(struct aa_dfa *dfa, unsigned int state,
struct aa_perms *perms)
{
- perms->deny = 0;
- perms->kill = perms->stop = 0;
- perms->complain = perms->cond = 0;
- perms->hide = 0;
- perms->prompt = 0;
- perms->allow = dfa_user_allow(dfa, state);
- perms->audit = dfa_user_audit(dfa, state);
- perms->quiet = dfa_user_quiet(dfa, state);
+ *perms = (struct aa_perms) {
+ .allow = dfa_user_allow(dfa, state),
+ .audit = dfa_user_audit(dfa, state),
+ .quiet = dfa_user_quiet(dfa, state),
+ };
/* for v5 perm mapping in the policydb, the other set is used
* to extend the general perm set
diff --git a/security/apparmor/mount.c b/security/apparmor/mount.c
index 82a64b58041d..ed9b4d0f9f7e 100644
--- a/security/apparmor/mount.c
+++ b/security/apparmor/mount.c
@@ -216,13 +216,12 @@ static unsigned int match_mnt_flags(struct aa_dfa *dfa, unsigned int state,
static struct aa_perms compute_mnt_perms(struct aa_dfa *dfa,
unsigned int state)
{
- struct aa_perms perms;
-
- perms.kill = 0;
- perms.allow = dfa_user_allow(dfa, state);
- perms.audit = dfa_user_audit(dfa, state);
- perms.quiet = dfa_user_quiet(dfa, state);
- perms.xindex = dfa_user_xindex(dfa, state);
+ struct aa_perms perms = {
+ .allow = dfa_user_allow(dfa, state),
+ .audit = dfa_user_audit(dfa, state),
+ .quiet = dfa_user_quiet(dfa, state),
+ .xindex = dfa_user_xindex(dfa, state),
+ };
return perms;
}