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authorPaul Moore <paul@paul-moore.com>2017-06-07 16:48:19 -0400
committerJames Morris <james.l.morris@oracle.com>2017-06-13 17:34:22 +1000
commit023f108dcc187e34ef864bf10ed966cf25e14e2a (patch)
tree6617c918c09d44b648db90e921844c9604de66f5
parent63f700aab4c11d46626de3cd051dae56cf7e9056 (diff)
downloadlinux-023f108dcc187e34ef864bf10ed966cf25e14e2a.tar.bz2
selinux: fix double free in selinux_parse_opts_str()
This patch is based on a discussion generated by an earlier patch from Tetsuo Handa: * https://marc.info/?t=149035659300001&r=1&w=2 The double free problem involves the mnt_opts field of the security_mnt_opts struct, selinux_parse_opts_str() frees the memory on error, but doesn't set the field to NULL so if the caller later attempts to call security_free_mnt_opts() we trigger the problem. In order to play it safe we change selinux_parse_opts_str() to call security_free_mnt_opts() on error instead of free'ing the memory directly. This should ensure that everything is handled correctly, regardless of what the caller may do. Fixes: e0007529893c1c06 ("LSM/SELinux: Interfaces to allow FS to control mount options") Cc: stable@vger.kernel.org Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Paul Moore <paul@paul-moore.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
-rw-r--r--security/selinux/hooks.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index e67a526d1f30..819fd6858b49 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1106,10 +1106,8 @@ static int selinux_parse_opts_str(char *options,
opts->mnt_opts_flags = kcalloc(NUM_SEL_MNT_OPTS, sizeof(int),
GFP_KERNEL);
- if (!opts->mnt_opts_flags) {
- kfree(opts->mnt_opts);
+ if (!opts->mnt_opts_flags)
goto out_err;
- }
if (fscontext) {
opts->mnt_opts[num_mnt_opts] = fscontext;
@@ -1132,6 +1130,7 @@ static int selinux_parse_opts_str(char *options,
return 0;
out_err:
+ security_free_mnt_opts(opts);
kfree(context);
kfree(defcontext);
kfree(fscontext);