| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.11 08/78] selinux: fix double free in selinux_parse_opts_str() | Date | Mon, 19 Jun 2017 23:15:08 +0800 |
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4.11-stable review patch. If anyone has any objections, please let me know.
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From: Paul Moore <paul@paul-moore.com>
commit 023f108dcc187e34ef864bf10ed966cf25e14e2a upstream.
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: 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- security/selinux/hooks.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
--- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -1106,10 +1106,8 @@ static int selinux_parse_opts_str(char * 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 * return 0; out_err: + security_free_mnt_opts(opts); kfree(context); kfree(defcontext); kfree(fscontext);
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