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selinux: free contexts previously transferred in selinux_add_opt() 

`selinux_add_opt()` stopped taking ownership of the passed context since
commit 70f4169ab4 ("selinux: parse contexts for mount options early").

    unreferenced object 0xffff888114dfd140 (size 64):
      comm "mount", pid 15182, jiffies 4295687028 (age 796.340s)
      hex dump (first 32 bytes):
        73 79 73 74 65 6d 5f 75 3a 6f 62 6a 65 63 74 5f  system_u:object_
        72 3a 74 65 73 74 5f 66 69 6c 65 73 79 73 74 65  r:test_filesyste
      backtrace:
        [<ffffffffa07dbef4>] kmemdup_nul+0x24/0x80
        [<ffffffffa0d34253>] selinux_sb_eat_lsm_opts+0x293/0x560
        [<ffffffffa0d13f08>] security_sb_eat_lsm_opts+0x58/0x80
        [<ffffffffa0af1eb2>] generic_parse_monolithic+0x82/0x180
        [<ffffffffa0a9c1a5>] do_new_mount+0x1f5/0x550
        [<ffffffffa0a9eccb>] path_mount+0x2ab/0x1570
        [<ffffffffa0aa019e>] __x64_sys_mount+0x20e/0x280
        [<ffffffffa1f47124>] do_syscall_64+0x34/0x80
        [<ffffffffa200007e>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

    unreferenced object 0xffff888108e71640 (size 64):
      comm "fsmount", pid 7607, jiffies 4295044974 (age 1601.016s)
      hex dump (first 32 bytes):
        73 79 73 74 65 6d 5f 75 3a 6f 62 6a 65 63 74 5f  system_u:object_
        72 3a 74 65 73 74 5f 66 69 6c 65 73 79 73 74 65  r:test_filesyste
      backtrace:
        [<ffffffff861dc2b1>] memdup_user+0x21/0x90
        [<ffffffff861dc367>] strndup_user+0x47/0xa0
        [<ffffffff864f6965>] __do_sys_fsconfig+0x485/0x9f0
        [<ffffffff87940124>] do_syscall_64+0x34/0x80
        [<ffffffff87a0007e>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

Cc: stable@vger.kernel.org
Fixes: 70f4169ab4 ("selinux: parse contexts for mount options early")
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Christian Göttsche 2022-06-15 17:38:39 +02:00 committed by Paul Moore
parent b13baccc38
commit cad140d008
1 changed files with 4 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
security/selinux/hooks.c
View File

@ -2600,8 +2600,9 @@ static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
} }
} }
rc = selinux_add_opt(token, arg, mnt_opts); rc = selinux_add_opt(token, arg, mnt_opts);
kfree(arg);
arg = NULL;
if (unlikely(rc)) { if (unlikely(rc)) {
kfree(arg);
goto free_opt; goto free_opt;
} }
} else { } else {
@ -2792,17 +2793,13 @@ static int selinux_fs_context_parse_param(struct fs_context *fc,
struct fs_parameter *param) struct fs_parameter *param)
{ {
struct fs_parse_result result; struct fs_parse_result result;
int opt, rc; int opt;
opt = fs_parse(fc, selinux_fs_parameters, param, &result); opt = fs_parse(fc, selinux_fs_parameters, param, &result);
if (opt < 0) if (opt < 0)
return opt; return opt;
rc = selinux_add_opt(opt, param->string, &fc->security); return selinux_add_opt(opt, param->string, &fc->security);
if (!rc)
param->string = NULL;
return rc;
} }
/* inode security operations */ /* inode security operations */